diff --git "a/hvac-error-codes.json" "b/hvac-error-codes.json" --- "a/hvac-error-codes.json" +++ "b/hvac-error-codes.json" @@ -1,13 +1,13 @@ { "name": "HVAC Bench Error Code Dataset", - "version": "1.0.0", - "dateModified": "2026-09-11", + "version": "1.1.0", + "dateModified": "2026-09-15", "publisher": "HVAC Bench", "url": "https://hvac-bench.com/data/hvac-error-codes/", "license": "CC-BY-4.0", "licenseUrl": "https://creativecommons.org/licenses/by/4.0/", "attribution": "HVAC Bench Error Code Dataset by HVAC Bench (https://hvac-bench.com), CC-BY-4.0", - "count": 87, + "count": 161, "columns": [ { "name": "id", @@ -103,6 +103,26 @@ "last_reviewed": "2026-09-03", "reference_url": "https://hvac-bench.com/brands/amana/ptac-br-code/" }, + { + "id": "brands/amana/ptac-diagnostic-codes", + "brand": "Amana", + "brand_slug": "amana", + "error_code": "Two-character codes", + "equipment_type": "ductless-mini-split", + "product_family": "Amana packaged terminal air conditioners and heat pumps covered by the Amana PTAC service literature", + "models": "Amana PTC series; Amana PTH series; Amana DigiSmart equipped units", + "fault_category": "not-turning-on", + "title": "Amana PTAC codes: two characters, and the second one matters", + "meaning": "Amana PTAC units display short two-character codes on the front panel, and both characters carry meaning. Reading only the first, or transcribing a letter as a digit, produces a lookup that lands on an unrelated entry, which is the most avoidable error in diagnosing this equipment.", + "scope_note": "Amana PTAC equipment spans cooling-only and heat pump models with different control generations, including units fitted with the DigiSmart control system. The service literature for the model on the chassis data plate is what maps a code, and a chart written for a different generation can give a different answer.", + "owner_safe_checks": "Photograph the display close up and read both characters from the image rather than from across the room. | Check that the supply cord is fully seated and whether any protective device on the plug has operated. | Clean the filter following the owner manual and clear anything obstructing the exterior grille that can be reached from outside.", + "call_a_technician_when": "Anything that requires the chassis to come out of the wall, or a meter to touch the board, belongs to a technician on equipment of this type. | A protective device on the supply cord that operates repeatedly is a stop condition rather than something to keep resetting, and it needs an electrical assessment.", + "reset_guidance": "Interrupting power clears the displayed code, so photograph it first. The unit re-tests its conditions on restart, and a code that returns is reporting something that has not changed.", + "evidence_class": "oem-support", + "evidence_publishers": "Amana", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/amana/ptac-diagnostic-codes/" + }, { "id": "brands/american-standard/s9v2-e21-error-code", "brand": "American Standard", @@ -123,6 +143,46 @@ "last_reviewed": "2026-09-03", "reference_url": "https://hvac-bench.com/brands/american-standard/s9v2-e21-error-code/" }, + { + "id": "brands/american-standard/furnace-fault-history-record", + "brand": "American Standard", + "brand_slug": "american-standard", + "error_code": "Stored fault history", + "equipment_type": "furnace", + "product_family": "American Standard gas furnaces whose integrated controls retain a stored fault history alongside the current status", + "models": "S9V2 series; Platinum series furnaces; Gold series furnaces", + "fault_category": "communication-fault", + "title": "American Standard fault history: the record outlasts the symptom", + "meaning": "An American Standard furnace control keeps a record of previous faults as well as reporting the current one, and that record survives the power interruptions people perform while troubleshooting. Where a fault is intermittent, the stored history is the only evidence that survives long enough to be diagnosed.", + "scope_note": "Fault history retention, and the method of retrieving it, differ between American Standard control platforms and between communicating and conventional systems. The service facts document for the exact furnace is the reference for how the history is read and how many entries are retained.", + "owner_safe_checks": "Photograph the diagnostic indication before interrupting power, even when you intend to reset the furnace afterwards. | Keep a dated note of each occasion heating has failed and how long it was unavailable. | Ask explicitly for the stored fault history to be retrieved during any service visit for an intermittent complaint.", + "call_a_technician_when": "Retrieving stored history requires access to the control and, on some platforms, a specific button sequence or service tool, which is a technician task. | Any entry concerning a limit, a rollout, or combustion is a stop condition regardless of the fact that heating has since resumed.", + "reset_guidance": "Interrupting power clears what is displayed and leaves the stored record intact, so a reset costs you the immediate code and nothing more. Photograph before resetting and the cost is nothing at all.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "American Standard; Trane", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/american-standard/furnace-fault-history-record/" + }, + { + "id": "brands/ariston/clas-overheat-fault-codes", + "brand": "Ariston", + "brand_slug": "ariston", + "error_code": "1-series", + "equipment_type": "boiler", + "product_family": "Ariston Clas gas boilers whose fault codes are grouped by leading digit in the Ariston user documentation", + "models": "Clas ONE; Clas ONE System; Clas Premium Evo; Clas HE", + "fault_category": "overheat-lockout", + "title": "Ariston Clas overheat codes: the 1-series group and what it points at", + "meaning": "Ariston organises Clas fault codes into groups by their leading digit, and the 1-series belongs to the primary water circuit. An overheat entry within that group therefore comes pre-labelled as a water-side condition, which is a genuinely useful piece of structure that most manufacturers do not offer.", + "scope_note": "The grouping described here is the one Ariston uses in Clas user documentation. Ariston sells other ranges with their own conventions, and appliances sold under related brand names are documented separately. Match the code to the manual issued with your own boiler before applying the grouping.", + "owner_safe_checks": "Record all three digits of the code exactly, since the leading digit and the pair that follow it do different jobs. | Read the system pressure gauge while the system is cold and write the figure down. | Feel each radiator after a heating attempt and map which heat, which do not, and where the cold begins on the panel.", + "call_a_technician_when": "Anything that restores flow through a sealed heating circuit, from a new circulator to a chemical clean, is Gas Safe registered work when it involves the appliance itself. | A boiler making boiling or knocking sounds should be left off rather than run while waiting, because those episodes deposit scale on the exchanger surface.", + "reset_guidance": "Ariston appliances allow a reset from the control panel. One attempt establishes whether the condition repeats; further attempts heat the exchanger under the same restricted flow that caused the trip.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Ariston", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/ariston/clas-overheat-fault-codes/" + }, { "id": "brands/ariston/clas-one-108-refill", "brand": "Ariston", @@ -163,6 +223,26 @@ "last_reviewed": "2026-09-03", "reference_url": "https://hvac-bench.com/brands/ariston/clas-one-error-501/" }, + { + "id": "brands/baxi/e110-overheat-lockout", + "brand": "Baxi", + "brand_slug": "baxi", + "error_code": "E110", + "equipment_type": "boiler", + "product_family": "Baxi domestic gas boilers using the E-series fault codes listed in Baxi support material", + "models": "Baxi 800 combi; Baxi 600 combi; Baxi Duo-tec; Baxi Platinum", + "fault_category": "overheat-lockout", + "title": "Baxi E110: the overheat lockout that is really a circulation message", + "meaning": "Baxi uses E110 for an overheat condition, where the boiler has exceeded its permitted maximum temperature or the safety thermostat has tripped. The measurement is genuine, but heat only accumulates when something stops carrying it away, so the investigation belongs to the water side of the system more often than to the burner.", + "scope_note": "Baxi publishes E-series codes across several domestic ranges, and the detail behind a number can differ between them. The list on the label behind the casing flap of your own appliance governs, and a Potterton or Main boiler from the same group carries its own published list even where components are shared.", + "owner_safe_checks": "Check the system pressure gauge on the boiler and write down the reading while the system is cold. | Feel every radiator after a heating attempt and record which warm up, which stay cold, and where on the panel the cold begins. | Note any noise from the boiler and whether it coincides with firing, and stop using the heating if kettling is present.", + "call_a_technician_when": "Pump testing and replacement, venting a sealed primary circuit, cleaning or flushing a system, and resetting a tripped safety thermostat are Gas Safe registered tasks. | A boiler that boils audibly should not be run while waiting for an appointment, because each episode damages the heat exchanger surface further.", + "reset_guidance": "Baxi permits a reset from the control panel, and one attempt establishes whether the lockout repeats. Repeating it against unchanged circulation subjects the exchanger to the same overheating each time.", + "evidence_class": "oem-support", + "evidence_publishers": "Baxi", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/baxi/e110-overheat-lockout/" + }, { "id": "brands/baxi/e119-low-pressure", "brand": "Baxi", @@ -203,6 +283,46 @@ "last_reviewed": "2026-09-03", "reference_url": "https://hvac-bench.com/brands/baxi/e133-fault-code/" }, + { + "id": "brands/baxi/e160-fan-fault", + "brand": "Baxi", + "brand_slug": "baxi", + "error_code": "E160", + "equipment_type": "boiler", + "product_family": "Baxi domestic gas boilers using the E-series fault codes listed in Baxi support material", + "models": "Baxi 800 combi; Baxi 600 combi; Baxi Duo-tec; Baxi EcoBlue", + "fault_category": "fan-fault", + "title": "Baxi E160: fan or fan wiring, and why the boiler will not compromise", + "meaning": "Baxi publishes E160 as a fan or fan wiring fault. Two distinct situations sit inside that phrase: a fan that is not turning at all, and a fan that is turning but whose speed the control cannot confirm. Both stop the boiler, and telling them apart from outside the casing starts with whether you can hear anything.", + "scope_note": "The E-series codes are published by Baxi across several domestic ranges, and the same number does not necessarily carry the same detail on every one. Read it against the list on the label behind your own casing flap, and treat lists compiled for other manufacturers as unrelated.", + "owner_safe_checks": "Stand near the boiler during one start attempt and note whether any fan sound occurs, and for how long. | Write the code down exactly, since Baxi E-series numbers are three digits and adjacent numbers mean different things. | Think back over the last few months for anyone who has worked on the appliance or the circuits feeding it, and note what they did.", + "call_a_technician_when": "Fan testing, wiring inspection, and fan replacement on a room-sealed gas appliance are Gas Safe registered tasks in the United Kingdom. | Leave the front of the appliance exactly as it is. That panel is part of the sealed enclosure separating combustion from room air, and it is not an inspection hatch.", + "reset_guidance": "A reset permits one further attempt, and the fan check happens within seconds of it. Where the fan cannot run or cannot be accepted, additional resets produce the same outcome without adding information.", + "evidence_class": "oem-support", + "evidence_publishers": "Baxi", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/baxi/e160-fan-fault/" + }, + { + "id": "brands/blueridge/bmkh-code-groups", + "brand": "Blueridge", + "brand_slug": "blueridge", + "error_code": "BMKH code groups", + "equipment_type": "ductless-mini-split", + "product_family": "Blueridge BMKH ductless mini-split systems documented in the Blueridge manual library", + "models": "BMKH wall-mounted indoor units; BMKH floor console indoor units; BMKH multi-zone systems", + "fault_category": "communication-fault", + "title": "Blueridge BMKH codes: a distributor brand with real documentation", + "meaning": "Blueridge publishes documentation per indoor unit style as well as per series, so a wall-mounted BMKH and a floor console BMKH carry different manuals. Reaching for the right one matters because indoor-side entries relate to hardware that differs between those styles even within the same model family.", + "scope_note": "Blueridge is a distributor brand whose equipment is documented under its own manuals rather than under the manufacturer that builds it. Those manuals are the reference, and documentation for visually similar equipment sold under another name is not a substitute.", + "owner_safe_checks": "Identify the indoor unit style and find the manual issued for that style rather than for the series in general. | Photograph the displayed code and both model numbers before interrupting power. | Switch to fan mode if condensate is visible, so the coil stops producing water while the fault is outstanding.", + "call_a_technician_when": "Condensate pumps, sensing elements, and fan assemblies sit inside indoor casings that also carry the supply, which makes access qualified work. | Conditions raised by the outdoor unit involve the refrigerant circuit and the drive, and both require certification to work on.", + "reset_guidance": "Cutting the supply once will show whether the report was latched or whether the condition is still live. Where condensate is involved, resist restarting in cooling afterwards, since every cycle sends more water into a path that has already fallen behind.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Alpine Home Air; Blueridge", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/blueridge/bmkh-code-groups/" + }, { "id": "brands/blueridge/bmkh-e1-error-code", "brand": "Blueridge", @@ -263,6 +383,86 @@ "last_reviewed": "2026-09-03", "reference_url": "https://hvac-bench.com/brands/bosch/climate-5000-pc30-pc31/" }, + { + "id": "brands/bosch/climate-5000-code-structure", + "brand": "Bosch", + "brand_slug": "bosch", + "error_code": "Prefix and digits", + "equipment_type": "ductless-mini-split", + "product_family": "Bosch Climate 5000 ductless mini-split systems documented in the Bosch service and manual library", + "models": "Climate 5000 single-zone; Climate 5000 multi-zone indoor units; Climate 5000 outdoor units", + "fault_category": "communication-fault", + "title": "Bosch Climate 5000: reading a code that names an indoor or outdoor origin", + "meaning": "Bosch Climate 5000 codes are built from a prefix and a pair of digits, and the prefix carries real information: it says whether the indoor unit, the outdoor unit, or the link between them raised the condition. Reading the prefix first narrows a search that would otherwise begin with the digits and end in the wrong table.", + "scope_note": "The Climate 5000 name covers single-zone and multi-zone equipment across more than one generation, and code assignments differ between them. Match the prefix and digits against the manual for the indoor and outdoor models on your data plates rather than against a chart for the range as a whole.", + "owner_safe_checks": "Photograph the indoor display so that the prefix and the digits are both captured together. | Copy the indoor and outdoor model numbers from their data plates before searching anything. | List any building work, decorating, or trades activity near the pipework or its cable route in recent months.", + "call_a_technician_when": "Interconnecting cable on this equipment carries mains voltage between the units, so inspecting, testing, or reterminating it is qualified work. | Outdoor protections reported through the indoor display involve the refrigerant circuit, which is certified activity rather than an owner check.", + "reset_guidance": "Power interruption clears the display and the system rebuilds its communication on restart, which makes one restart a genuine test. Capture the full code first, because the display is the only place it appears.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Bosch Home Comfort", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/bosch/climate-5000-code-structure/" + }, + { + "id": "brands/bryant/evolution-communication-loss", + "brand": "Bryant", + "brand_slug": "bryant", + "error_code": "Communication loss", + "equipment_type": "controls-thermostats", + "product_family": "Bryant Evolution communicating systems using the Evolution Connex control and a four-conductor communication bus", + "models": "Evolution Connex control; Evolution communicating gas furnaces; Evolution communicating heat pumps and air conditioners", + "fault_category": "communication-fault", + "title": "Bryant Evolution communication loss: when the system stops talking to itself", + "meaning": "A Bryant Evolution system is not a thermostat with switched wires. The control, the indoor unit, and the outdoor unit exchange data over a shared bus, and losing that conversation stops coordinated operation even when every individual component is healthy. A communication message therefore points at the path between devices before it points at any device.", + "scope_note": "This describes the communicating architecture Bryant uses for Evolution systems. A Bryant system with a conventional thermostat and individually switched conductors does not behave this way, and the Carrier equivalent of the same architecture carries its own message set. Confirm you have a communicating control before applying it.", + "owner_safe_checks": "Write down the exact message the wall control shows, including any number or reference it displays alongside it. | Establish whether heating or cooling still happens at all, and whether output varies or sits at one fixed level. | Note any recent storms, flooding, landscaping, or building work near the outdoor unit or the cable route between units.", + "call_a_technician_when": "Testing a communication bus, inspecting outdoor terminal blocks, and replacing damaged interconnecting cable are tasks inside enclosures carrying line voltage. | Do not substitute a conventional thermostat for a communicating control to restore operation. The equipment expects data on those conductors, not switched voltage.", + "reset_guidance": "Restoring power re-establishes the conversation if the path is intact, so a message that clears and returns is describing a connection that is marginal rather than one that has been repaired.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Bryant", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/bryant/evolution-communication-loss/" + }, + { + "id": "brands/carrier/furnace-status-code-13-limit-lockout", + "brand": "Carrier", + "brand_slug": "carrier", + "error_code": "13", + "equipment_type": "furnace", + "product_family": "Carrier deluxe two-stage gas-fired induced-combustion furnaces with PSC or ICM blower motors, as covered by troubleshooting guide 58-3T", + "models": "Deluxe two-stage induced-combustion furnaces with PSC blower; Deluxe two-stage induced-combustion furnaces with ICM blower", + "fault_category": "limit-circuit-lockout", + "title": "Carrier status code 13: the lockout that follows a limit or rollout switch", + "meaning": "Carrier lists status code 13 as a limit or flame rollout switch lockout. The control had already seen that circuit open, reported it, and then decided the condition had lasted long enough to stop trying. A lockout is a deliberate refusal to restart, so code 13 is a stronger statement than the open-circuit code that precedes it.", + "scope_note": "This reading is taken from Carrier troubleshooting guide 58-3T, which covers deluxe two-stage gas-fired induced-combustion furnaces with PSC or ICM blower motors. Other Carrier furnace controls, and the same numbers on Bryant or Payne equipment, are read from their own literature. Confirm the model on the furnace rating plate first.", + "owner_safe_checks": "With the furnace switched off, inspect the return-air filter and fit a clean one of the specified size and type if it is loaded. | Walk the house and confirm that supply registers and return grilles are open and not covered by furniture, rugs, or stored items. | Record the flash pattern through the sight glass without opening the blower door, along with the date and time of the lockout.", + "call_a_technician_when": "Identifying which safety device opened, measuring temperature rise, and inspecting combustion and venting are licensed gas-furnace tasks. | Treat soot, scorching, an odour of combustion products, or a carbon monoxide alarm as an immediate stop. Get fresh air into the space, keep the appliance off, and use the emergency number your gas supplier publishes.", + "reset_guidance": "Carrier's control clears a lockout on its own after a fixed interval, so an automatic retry proves nothing about the underlying condition. Interrupting power to force an earlier retry removes the record without changing the circuit.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Carrier", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/carrier/furnace-status-code-13-limit-lockout/" + }, + { + "id": "brands/carrier/furnace-status-code-14-ignition-lockout", + "brand": "Carrier", + "brand_slug": "carrier", + "error_code": "14", + "equipment_type": "furnace", + "product_family": "Carrier deluxe two-stage gas-fired induced-combustion furnaces with PSC or ICM blower motors, covered by troubleshooting guide 58-3T", + "models": "Deluxe two-stage induced-combustion furnaces, PSC blower; Deluxe two-stage induced-combustion furnaces, ICM blower", + "fault_category": "ignition-lockout", + "title": "Carrier status code 14: ignition lockout after four failed trials", + "meaning": "Status code 14 on this Carrier control is ignition lockout. The guide states that lockout occurs after four consecutive unsuccessful trials for ignition and that the control resets itself automatically after three hours. The number 14 therefore counts failures; it does not identify which part of the ignition sequence failed.", + "scope_note": "The count of four trials and the three-hour automatic reset are stated in Carrier troubleshooting guide 58-3T for deluxe two-stage induced-combustion furnaces. Single-stage and modulating Carrier controls, and the same number on other manufacturers, follow their own literature and their own retry counts.", + "owner_safe_checks": "Confirm that other gas appliances in the property are working normally, which separates a supply-wide interruption from a furnace-specific fault. | Check that the thermostat is calling for heat and that its batteries, if fitted, are good, so a failed call is not mistaken for a failed ignition. | Note the time of each lockout and the weather conditions, then leave the furnace off rather than forcing repeated retries.", + "call_a_technician_when": "Measuring gas pressure, testing igniter resistance, cleaning or replacing a flame sensor, and inspecting venting are licensed gas-furnace tasks. | A smell of gas at any point is an emergency. Leave the property, avoid switches and flames, and contact the emergency number for your gas supplier before anything else.", + "reset_guidance": "Carrier's control releases this lockout automatically after three hours. Cutting power to force an earlier retry only spends four more trials against the same condition and erases the diagnostic record.", + "evidence_class": "oem-service-manual", + "evidence_publishers": "Carrier", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/carrier/furnace-status-code-14-ignition-lockout/" + }, { "id": "brands/carrier/infinity-code-16-with-53-55-47", "brand": "Carrier", @@ -283,6 +483,26 @@ "last_reviewed": "2026-09-04", "reference_url": "https://hvac-bench.com/brands/carrier/infinity-code-16-with-53-55-47/" }, + { + "id": "brands/carrier/furnace-status-code-24-fuse-open", + "brand": "Carrier", + "brand_slug": "carrier", + "error_code": "24", + "equipment_type": "furnace", + "product_family": "Carrier deluxe two-stage gas-fired induced-combustion furnaces with PSC or ICM blower motors, per troubleshooting guide 58-3T", + "models": "Deluxe two-stage induced-combustion furnaces with PSC blower motors; Deluxe two-stage induced-combustion furnaces with ICM blower motors", + "fault_category": "control-power-fault", + "title": "Carrier status code 24: the secondary voltage fuse is open", + "meaning": "Carrier defines status code 24 as the secondary voltage fuse being open. That fuse protects the 24-volt control circuit, and the guide specifies a 3 amp automotive blade type that must be replaced only with another 3 amp fuse. A fuse opens because something drew more current than the circuit allows, so the fuse is the symptom.", + "scope_note": "The fuse rating and the code definition come from Carrier troubleshooting guide 58-3T for deluxe two-stage induced-combustion furnaces. Fuse ratings differ between control platforms, and fitting anything other than the rating in the literature for your exact model removes the protection the circuit was designed around.", + "owner_safe_checks": "Establish exactly what has stopped: heating alone, heating and cooling together, or any accessory such as a humidifier. | Check whether the thermostat display is blank or still powered, since that alone tells the technician which side of the circuit lost supply. | Write down any recent work on thermostats, cabling, outdoor equipment, or the building fabric in the weeks beforehand.", + "call_a_technician_when": "Locating a short in the 24-volt circuit, testing the transformer, and replacing the control fuse are tasks inside an enclosure that also carries line voltage, so they belong to a qualified technician. | Never fit a fuse of a higher rating than the literature specifies. The protection the original rating provides is the reason the transformer and board survived the fault.", + "reset_guidance": "There is nothing to reset here. The circuit stays open until the fuse is replaced, and replacing it without finding the short simply repeats the event.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Carrier", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/carrier/furnace-status-code-24-fuse-open/" + }, { "id": "brands/carrier/furnace-status-code-31", "brand": "Carrier", @@ -303,6 +523,26 @@ "last_reviewed": "2026-09-09", "reference_url": "https://hvac-bench.com/brands/carrier/furnace-status-code-31/" }, + { + "id": "brands/carrier/furnace-status-code-32-pressure-switch", + "brand": "Carrier", + "brand_slug": "carrier", + "error_code": "32", + "equipment_type": "furnace", + "product_family": "Carrier deluxe two-stage gas-fired induced-combustion furnaces with PSC or ICM blower motors, per troubleshooting guide 58-3T", + "models": "Deluxe two-stage induced-combustion upflow furnaces; Deluxe two-stage induced-combustion downflow furnaces; Deluxe two-stage induced-combustion horizontal furnaces", + "fault_category": "pressure-switch-fault", + "title": "Carrier status code 32: three switches share one number", + "meaning": "Carrier writes status code 32 as the low-heat pressure switch, the draft safeguard switch, or the downflow auxiliary limit switch failing to close or reopening after it had closed. Three separate devices share the entry, and the control cannot tell you which one acted, so the code narrows the fault to a group rather than to a part.", + "scope_note": "Guide 58-3T is the source here, and it covers deluxe two-stage induced-combustion equipment only. The auxiliary limit named in the entry is present on downflow arrangements, so what the code can mean depends on how your furnace is installed as well as on which model it is.", + "owner_safe_checks": "Look at the outdoor vent and intake terminations from ground level and note any ice, snow, nesting material, or vegetation without attempting to clear anything at height. | Time how long the furnace produces heat before it stops, and whether the burners lit at all. | Keep a short log of the outdoor temperature and wind conditions each time the code appears.", + "call_a_technician_when": "Measuring draft pressure, inspecting the vent system, clearing condensate traps, and testing pressure switches are licensed gas-furnace tasks. | Combustion products detected indoors, or a carbon monoxide alarm sounding, outranks every other instruction on this page. Get people out, open up the space, and call the emergency line your gas supplier publishes.", + "reset_guidance": "Interrupting power clears the display, and the control then re-tests the same circuit at the next call for heat. Where a draft safeguard may be involved, repeated retries are the wrong response regardless of whether they appear to work.", + "evidence_class": "oem-service-manual", + "evidence_publishers": "Carrier", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/carrier/furnace-status-code-32-pressure-switch/" + }, { "id": "brands/carrier/58mcb-code-33-limit-circuit-fault", "brand": "Carrier", @@ -323,6 +563,26 @@ "last_reviewed": "2026-09-09", "reference_url": "https://hvac-bench.com/brands/carrier/58mcb-code-33-limit-circuit-fault/" }, + { + "id": "brands/carrier/furnace-status-code-34-ignition-proving", + "brand": "Carrier", + "brand_slug": "carrier", + "error_code": "34", + "equipment_type": "furnace", + "product_family": "Carrier deluxe two-stage gas-fired induced-combustion furnaces with PSC or ICM blower motors, per troubleshooting guide 58-3T", + "models": "Deluxe two-stage induced-combustion furnaces, natural gas; Deluxe two-stage induced-combustion furnaces, propane", + "fault_category": "ignition-lockout", + "title": "Carrier status code 34: ignition proving failed on this trial", + "meaning": "Carrier lists status code 34 as an ignition-proving fault. It records that a trial for ignition did not end with a proven flame, and unlike code 14 it does not mean the control has given up. Seeing 34 without 14 means the furnace is still retrying, which is the moment when observing what happens is worth most.", + "scope_note": "Read here from Carrier troubleshooting guide 58-3T for deluxe two-stage induced-combustion furnaces. The relationship between the per-trial fault and the lockout that follows it is specific to this control family, and other manufacturers using the number 34 are not describing the same thing.", + "owner_safe_checks": "Listen to a full heating cycle from a safe distance and note whether a flame is established at all, and whether it is lost after establishing. | Keep a tally over several days of how many heat calls succeed and how many fail, with the times of day. | Confirm that other gas appliances behave normally and note whether failures coincide with their use.", + "call_a_technician_when": "Measuring the flame signal, testing igniter resistance, cleaning a sensing electrode, and checking manifold gas pressure are licensed gas-furnace tasks. | Any smell of gas requires the emergency response for your supplier before any further troubleshooting: leave the property, avoid switches, and call from outside.", + "reset_guidance": "Code 34 is a per-trial record rather than a latched state, so the furnace continues retrying without intervention. Clearing it by interrupting power removes the history that shows how the fault is progressing.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Carrier", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/carrier/furnace-status-code-34-ignition-proving/" + }, { "id": "brands/cooper-and-hunter/sophia-cassette-e1-error", "brand": "Cooper & Hunter", @@ -343,6 +603,46 @@ "last_reviewed": "2026-09-03", "reference_url": "https://hvac-bench.com/brands/cooper-and-hunter/sophia-cassette-e1-error/" }, + { + "id": "brands/cooper-and-hunter/f-series-sensing-codes", + "brand": "Cooper & Hunter", + "brand_slug": "cooper-and-hunter", + "error_code": "F-series", + "equipment_type": "ductless-mini-split", + "product_family": "Cooper and Hunter ductless mini-split systems documented in the Cooper and Hunter support library", + "models": "Sophia series; Astoria series; Olivia series; Mia series", + "fault_category": "temperature-sensor-fault", + "title": "Cooper and Hunter F codes: a sensing family shared across the range", + "meaning": "Cooper and Hunter groups its sensing faults into an F-series, where the letter marks a temperature sensing problem and the digit identifies which sensor position the control was reading. Every entry in the family shares the same meaning at the level of the letter: a reading the control will not act on.", + "scope_note": "Cooper and Hunter sells several ductless ranges and publishes documentation per range rather than as one list. The digit following the F identifies a sensor position within the model's own scheme, so the support document for your series is what maps it. Ranges from other suppliers using similar lettering are unrelated.", + "owner_safe_checks": "Photograph the display showing the complete code, letter and digit together, before power is interrupted. | Compare the temperature the indoor unit reports against a separate thermometer and note both figures. | Record which indoor unit is affected and whether any others on the system are behaving oddly.", + "call_a_technician_when": "Sensing elements, their connectors, and the harnesses linking them to the board sit inside casings that also carry mains supply, so access is qualified work. | An outdoor sensing fault can accompany water ingress into the enclosure, which needs assessing beyond the sensing element itself.", + "reset_guidance": "The reading is taken again on the next start, so a code that returns immediately is describing an unchanged resistance. Capture the code before interrupting power, since the display is where it lives.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Cooper and Hunter", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/cooper-and-hunter/f-series-sensing-codes/" + }, + { + "id": "brands/daikin/a3-drain-level-control", + "brand": "Daikin", + "brand_slug": "daikin", + "error_code": "A3", + "equipment_type": "ductless-mini-split", + "product_family": "Daikin indoor units covered by the SM-TS3 malfunction code chart, spanning room air, SkyAir, and VRV indoor equipment", + "models": "FXFQ series cassettes; FXMQ series ducted; FXSQ series ducted; FXZQ series cassettes", + "fault_category": "water-leak", + "title": "Daikin A3: drain level control abnormality on the indoor unit", + "meaning": "Daikin assigns A3 to the drain level control system in the indoor unit division of its malfunction chart. The control detected that the condensate level or the drain system response was outside normal, and it stopped operation to prevent the tray overflowing. The chart names the system, which is why A3 covers the float switch, the drain pump, and the path between them rather than any one of them.", + "scope_note": "A3 is read from the Daikin After Sales Service malfunction code chart, which divides codes by unit rather than by model. The chart gives the meaning of the letter and detail code; the component layout behind it comes from the service manual for the specific indoor unit. A wall-mounted room air unit without a drain pump does not carry the same detection.", + "owner_safe_checks": "Select fan operation or switch the affected indoor unit off so the coil stops condensing while the fault is outstanding. | Record the unit number shown beside A3 and the room that unit serves, which identifies the address for service. | Check whether the external condensate discharge point produced any water during the period the unit had been cooling.", + "call_a_technician_when": "Opening a cassette decoration panel, testing a float switch, or clearing a drain pan inside the indoor unit is qualified service work on this equipment. | Any water that has reached ceiling material, lighting, or an electrical accessory is a stop condition, and the indoor unit should be isolated rather than restarted.", + "reset_guidance": "Clearing the display resets the report, not the level. One restart may confirm the fault repeats; further restarts add condensate to a tray the system has already declared it cannot empty.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Daikin Industries", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/daikin/a3-drain-level-control/" + }, { "id": "brands/daikin/a5-error-code", "brand": "Daikin", @@ -363,6 +663,86 @@ "last_reviewed": "2026-09-02", "reference_url": "https://hvac-bench.com/brands/daikin/a5-error-code/" }, + { + "id": "brands/daikin/a6-indoor-fan-motor", + "brand": "Daikin", + "brand_slug": "daikin", + "error_code": "A6", + "equipment_type": "ductless-mini-split", + "product_family": "Daikin indoor units covered by the SM-TS3 malfunction chart, including room air, SkyAir, and VRV indoor equipment", + "models": "FTXS series wall units; FXFQ series cassettes; FXMQ series ducted; FTXM series wall units", + "fault_category": "not-turning-on", + "title": "Daikin A6: indoor fan motor locked, overloaded, or badly connected", + "meaning": "Daikin lists A6 in the indoor unit division as a fan motor malfunction, described as the motor being locked, overloaded, or suffering from a faulty connection. All three are ways of saying the board commanded a fan speed and did not get the feedback it expected, so the code is about the command-and-feedback loop rather than about a burnt-out motor.", + "scope_note": "The definition here comes from the Daikin malfunction code chart, which is organised by division and detail code rather than by model. Indoor fan arrangements differ sharply between a wall unit, a cassette, and a ducted unit, so the mechanical cause behind the same code is model-specific and is read from that unit's service manual.", + "owner_safe_checks": "Switch the affected indoor unit off and leave it off, since running the outdoor unit against a stalled indoor coil is what the protection prevents. | Confirm the filters, front panel, and any decoration panel are correctly seated and latched after recent cleaning. | Write down any noise heard before the fault, the fan speed it occurred at, and roughly when it started.", + "call_a_technician_when": "Reaching into the fan housing, freeing a wheel, and testing motor feedback or winding condition require the indoor casing to be opened by a qualified technician. | Do not attempt to turn the fan wheel by hand through a grille or outlet. The blade edges and the drive arrangement are not designed for that access.", + "reset_guidance": "The code clears from the display on a power interruption, but the board re-tests the fan on the next start, so a fault that returns within seconds is reporting an unchanged mechanical or electrical condition.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Daikin Industries; Daikin Comfort Technologies", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/daikin/a6-indoor-fan-motor/" + }, + { + "id": "brands/daikin/c9-suction-air-thermistor", + "brand": "Daikin", + "brand_slug": "daikin", + "error_code": "C9", + "equipment_type": "ductless-mini-split", + "product_family": "Daikin indoor units covered by the SM-TS3 malfunction chart, where the C division covers sensor systems", + "models": "FTXS series; FTXM series; FXFQ series; FXMQ series", + "fault_category": "temperature-sensor-fault", + "title": "Daikin C9: the suction air thermistor the room setting depends on", + "meaning": "Daikin places C9 in the sensor division against the suction air thermistor, and describes the fault as an abnormal resistance, which covers a disconnection and a short circuit. That sensor reads the air entering the indoor unit, so it is the value the system treats as room temperature and the basis of every capacity decision it makes.", + "scope_note": "The C division on the Daikin chart groups sensor systems, and the detail code selects which sensor. Where a sensor sits inside a particular indoor unit, and what resistance curve it follows, comes from the service manual for that model. A code alone does not tell a technician which physical part to reach for.", + "owner_safe_checks": "Note the unit number shown beside C9 and which room it serves before any power is interrupted. | Compare the temperature the controller displays, if it is still visible, against a separate thermometer near the intake. | Confirm filters and panels are correctly seated, and note whether the fault followed any recent cleaning or service.", + "call_a_technician_when": "Measuring thermistor resistance against the published curve and inspecting the indoor board connectors require the casing to be opened by a qualified technician. | A code accompanied by a burning smell, discoloration, or a protective device operating is a stop condition rather than a sensor question.", + "reset_guidance": "The resistance is measured again on the next start, so clearing the display does not change the outcome. A code returning immediately confirms the reading is still outside the accepted band.", + "evidence_class": "oem-service-manual", + "evidence_publishers": "Daikin Industries", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/daikin/c9-suction-air-thermistor/" + }, + { + "id": "brands/daikin/e7-outdoor-fan-motor", + "brand": "Daikin", + "brand_slug": "daikin", + "error_code": "E7", + "equipment_type": "heat-pump", + "product_family": "Daikin outdoor units covered by the SM-TS3 malfunction chart, including room air, SkyAir, and VRV outdoor equipment", + "models": "RXS series; RXM series; RZQ series; RZR series", + "fault_category": "outdoor-unit-not-running", + "title": "Daikin E7: the outdoor fan motor system stopped reporting what it should", + "meaning": "Daikin places E7 in the outdoor unit division as a malfunction of the outdoor fan motor system. The word system is doing real work in that phrase: the entry covers the motor, the drive circuit that powers it, and the feedback path that confirms it turned. Seeing the fan stationary confirms the symptom but not the cause.", + "scope_note": "This meaning is taken from the Daikin malfunction code chart, which assigns codes by division rather than by model. Outdoor fan arrangements differ between a single-fan room air unit and a twin-fan SkyAir or VRV frame, and the checks for each come from the service manual covering that outdoor model.", + "owner_safe_checks": "Stop the system from the controller so it is not making repeated start attempts against a fan that is not turning. | Look at the outdoor unit from a safe distance and note whether the blade is completely static, turning slowly, or turning normally. | Isolate the outdoor unit at its dedicated switch before removing leaves or debris resting against the outside of the guard.", + "call_a_technician_when": "Testing the fan drive output, measuring motor windings, and inspecting feedback wiring inside an outdoor enclosure are energised tasks for a qualified technician. | Never reach through or remove the fan guard. A variable-speed outdoor fan can start without notice, including while the system appears to be idle.", + "reset_guidance": "A restart re-tests the fan within seconds, so the code returning quickly means the condition has not changed. Repeated attempts run the compressor briefly with no heat rejection, which is worth avoiding.", + "evidence_class": "oem-service-manual", + "evidence_publishers": "Daikin Industries; Daikin Comfort Technologies", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/daikin/e7-outdoor-fan-motor/" + }, + { + "id": "brands/daikin/f3-discharge-pipe-temperature", + "brand": "Daikin", + "brand_slug": "daikin", + "error_code": "F3", + "equipment_type": "heat-pump", + "product_family": "Daikin outdoor equipment covered by the SM-TS3 malfunction chart, spanning room air, SkyAir, and VRV outdoor units", + "models": "RXS series; RXM series; RZQ series; RXYQ series", + "fault_category": "protection-shutdown", + "title": "Daikin F3: discharge pipe temperature outside what the circuit allows", + "meaning": "Daikin's malfunction chart lists F3 against discharge pipe temperature. The thermistor on the compressor discharge line has reported a temperature the control will not run at, and because refrigerant flow is what keeps that line cool, the reading is a statement about the circuit rather than about the pipe.", + "scope_note": "Taken from the Daikin After Sales Service malfunction chart, where the F division belongs to the outdoor unit and the detail code selects the subsystem. Sensor positions and the thresholds behind them come from the service manual for the specific outdoor model, so a code alone does not give you a temperature to compare against.", + "owner_safe_checks": "Stop calling for heating or cooling and leave the system off, since each further cycle runs the compressor toward the same limit. | Walk the visible line set and outdoor unit looking for oil film or localised frost, and photograph anything unusual without touching it. | Record how long the outdoor unit runs before it stops, and how performance had changed over the preceding weeks.", + "call_a_technician_when": "Charge measurement, leak detection, recovery, and discharge thermistor testing are certified refrigerant activities under EPA Section 608 and under F-Gas rules in the United Kingdom and European Union. | Adding refrigerant without finding the loss, or restarting to see whether the code stays away, both put the compressor back into the condition the protection stopped.", + "reset_guidance": "Power cycling clears the stored code and the protection re-evaluates on the next run. Because the measured temperature is a live condition, a code that returns quickly means nothing has changed in the circuit.", + "evidence_class": "oem-service-manual", + "evidence_publishers": "Daikin Industries; Daikin Comfort Technologies", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/daikin/f3-discharge-pipe-temperature/" + }, { "id": "brands/daikin/u0-refrigerant-shortage", "brand": "Daikin", @@ -376,13 +756,33 @@ "meaning": "Daikin assigns U0 to a refrigerant shortage. The control has seen the circuit behaving as though there is too little refrigerant, from readings such as a low suction temperature or an abnormal discharge condition. A closed service valve, an undercharge left after install, or a leak all present as U0.", "scope_note": "This meaning follows the Daikin malfunction code table for room air conditioner and multi-split systems that list U0. SkyAir, VRV, and Altherma ranges use their own code sets, so confirm the indoor and outdoor model numbers before applying this page.", "owner_safe_checks": "Note whether the system is newly installed or has a long service history, and whether output faded gradually or stopped suddenly before U0. | Check from the ground for oily residue at pipe joints or unusual frosting on the outdoor unit, without touching the pipework or valves.", - "call_a_technician_when": "Checking stop valves, leak testing, evacuating, and weighing in refrigerant all require a technician with gauges and a refrigerant handling qualification.", + "call_a_technician_when": "Refrigerant-circuit diagnosis and charging require a qualified technician with the applicable refrigerant handling credential.", "reset_guidance": "Clearing U0 with a power cycle does not add refrigerant. If the code returns, the circuit is still short and the diagnosis needs gauges rather than another reset.", "evidence_class": "mixed-primary-sources", "evidence_publishers": "Daikin Comfort Technologies; Daikin Industries", "last_reviewed": "2026-09-09", "reference_url": "https://hvac-bench.com/brands/daikin/u0-refrigerant-shortage/" }, + { + "id": "brands/daikin/u2-power-supply-fault", + "brand": "Daikin", + "brand_slug": "daikin", + "error_code": "U2", + "equipment_type": "heat-pump", + "product_family": "Daikin equipment covered by the SM-TS3 malfunction chart, where the U division reports system-level conditions across room air, SkyAir, and VRV", + "models": "RXS series; RZQ series; RXYQ series; FTXS series", + "fault_category": "voltage-protection", + "title": "Daikin U2: power supply malfunction or an instantaneous power failure", + "meaning": "In the Daikin malfunction chart, U2 belongs to the system division and reads as a malfunction of the power supply or an instantaneous power failure. That covers both a supply that briefly disappeared and a supply that is present but outside what the drive will work with, which is why one U2 after a storm and a U2 that repeats every day mean unrelated things.", + "scope_note": "The reading is taken from the Daikin After Sales Service chart, where the U division covers system conditions rather than one unit. Some Daikin equipment, including the room air lines, presents a related shortage entry as U0, so confirm which digit is displayed before treating the fault as electrical.", + "owner_safe_checks": "Check whether a power cut, a storm, or electrical work coincided with the code, and write down what you find. | Confirm that the dedicated isolator and any protective device serving the equipment are in their normal operating position. | Read the supply voltage and frequency printed on the outdoor unit data plate so the figures are available to service.", + "call_a_technician_when": "Measuring supply voltage under load, inspecting isolator and terminal connections, and testing the drive input are qualified electrical tasks. | A protective device that operates repeatedly, a burning smell, or heat at an isolator is a stop condition. Leave the supply off and arrange an electrical inspection.", + "reset_guidance": "One restart is the accepted test for this entry because the chart includes an instantaneous power failure. If the code returns after that single attempt, leave the system off and treat the supply as the subject of the investigation.", + "evidence_class": "oem-service-manual", + "evidence_publishers": "Daikin Industries", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/daikin/u2-power-supply-fault/" + }, { "id": "brands/daikin/u4-error-code", "brand": "Daikin", @@ -463,6 +863,26 @@ "last_reviewed": "2026-09-03", "reference_url": "https://hvac-bench.com/brands/daikin-altherma/7h-water-flow-subcodes/" }, + { + "id": "brands/daikin-altherma/hot-water-duty-faults", + "brand": "Daikin Altherma", + "brand_slug": "daikin-altherma", + "error_code": "Hot water duty conditions", + "equipment_type": "heat-pump", + "product_family": "Daikin Altherma air-to-water heat pump systems serving space heating and a domestic hot water cylinder", + "models": "Altherma 3 H HT; Altherma 3 R; Altherma 3 M; Altherma integrated cylinder units", + "fault_category": "no-heating", + "title": "Daikin Altherma hot water faults: two duties competing for one machine", + "meaning": "An Altherma serves space heating and the hot water cylinder from one heat pump, and it cannot do both at once. Priority settings decide which duty wins, so heating that pauses during a cylinder reheat, or hot water that takes longer than a boiler did, is the system working as designed rather than reporting a fault.", + "scope_note": "Altherma covers split, monobloc, and integrated cylinder configurations across several generations, with different controllers and different parameter names. The installation and operation manual for your configuration governs, and hot water behaviour in particular depends on commissioning choices as much as on the hardware.", + "owner_safe_checks": "Note whether space heating pauses coincide with hot water production, which distinguishes priority switching from a fault. | Time a full cylinder reheat and record the cylinder temperature setting alongside it. | Check whether a disinfection cycle is scheduled and at what time, since that is when the element is expected to run.", + "call_a_technician_when": "Cylinder temperature settings, priority parameters, and disinfection schedules affect both safety and running cost, and the installer who commissioned the system should change them. | Anything on the sealed refrigerant side of an Altherma needs a certified handler, regardless of whether the symptom appears on the hot water side.", + "reset_guidance": "Priority switching and disinfection cycles are scheduled behaviour with nothing to reset. Confirm that a genuine fault code is displayed before treating the pattern as a failure.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Daikin UK; Daikin", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/daikin-altherma/hot-water-duty-faults/" + }, { "id": "brands/della/outdoor-sensor-error-codes", "brand": "Della", @@ -503,6 +923,126 @@ "last_reviewed": "2026-09-03", "reference_url": "https://hvac-bench.com/brands/della/e5-error-code-by-series/" }, + { + "id": "brands/della/error-codes-by-series", + "brand": "Della", + "brand_slug": "della", + "error_code": "Series-dependent codes", + "equipment_type": "ductless-mini-split", + "product_family": "Della ductless mini-split systems documented in the Della manual and support library", + "models": "Della single-zone wall units; Della multi-zone indoor units; Della outdoor condensing units", + "fault_category": "communication-fault", + "title": "Della codes: a value brand still needs the right document", + "meaning": "Della supports its equipment through documentation tied to each product line rather than through a single brand-wide code list. An owner therefore needs the model number before the code means anything, and that is the step most likely to be skipped on lower-cost equipment where the manual has been discarded.", + "scope_note": "Della equipment is manufactured to order and its documentation is organised per model. A code list found under the brand name alone may describe a different product line, and the manual or support document that matches the model number on the data plate is the only reliable mapping.", + "owner_safe_checks": "Photograph both data plates and record the complete model numbers before contacting anybody. | Photograph the displayed code before power is interrupted for any reason. | Note whether the system fails at startup or after a period of operation, and how long it ran.", + "call_a_technician_when": "The conductors linking the wall unit to the condenser sit at mains potential, which puts any probing, stripping, or reterminating of them outside owner work. | Conditions reached after a period of operation involve the sealed refrigerant circuit, which requires certification to open regardless of what the equipment cost.", + "reset_guidance": "One power interruption distinguishes a latched report from a live condition on this equipment as on any other. Photograph the code first, because on a system with no accessible chart the display is the only record you have.", + "evidence_class": "oem-support", + "evidence_publishers": "Della Home", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/della/error-codes-by-series/" + }, + { + "id": "brands/drayton/one-room-not-heating", + "brand": "Drayton", + "brand_slug": "drayton", + "error_code": "Room demand not met", + "equipment_type": "controls-thermostats", + "product_family": "Drayton Wiser multi-zone heating systems using a heat hub with room thermostats and smart radiator thermostats", + "models": "Wiser Heat Hub; Wiser Room Thermostat; Wiser Smart Radiator Thermostat", + "fault_category": "communication-fault", + "title": "Drayton Wiser: one cold room when the rest of the house is warm", + "meaning": "A Wiser system asks the boiler for heat only when at least one room wants it, and then opens that room's radiator valves. A single cold room therefore means either that room is not asking, or it is asking and its valve is not opening, and those are separate faults with separate fixes.", + "scope_note": "Wiser covers single-zone and multi-zone arrangements with different combinations of hub, room thermostats, and radiator thermostats, and behaviour depends on how the system was configured rather than only on what is installed. The Drayton Wiser documentation for your arrangement is the reference.", + "owner_safe_checks": "Confirm whether the rest of the house heats normally during the same period, which separates a room fault from a system fault. | Check and replace the batteries in the affected radiator thermostat, since a device without power cannot move a valve. | Listen at the radiator when a demand is set, since a valve that is being driven makes an audible movement.", + "call_a_technician_when": "A radiator that stays cold with its valve confirmed open, or that is cold at the bottom while hot at the top, is a hydraulic matter for a heating engineer. | Removing a radiator thermostat from a valve body, or changing a valve, risks releasing water from a sealed system and sits outside owner maintenance.", + "reset_guidance": "Removing and refitting batteries reconnects a device that has lost its link and does nothing for a valve that cannot move. Establish whether the valve is being driven before pairing anything again.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Drayton Controls; Schneider Electric", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/drayton/one-room-not-heating/" + }, + { + "id": "brands/ecobee/threshold-and-staging-alerts", + "brand": "ecobee", + "brand_slug": "ecobee", + "error_code": "Alerts and reminders", + "equipment_type": "controls-thermostats", + "product_family": "ecobee smart thermostats with installer settings governing staging, thresholds, and equipment lockouts", + "models": "ecobee Smart Thermostat Premium; ecobee Smart Thermostat Enhanced; ecobee3 lite", + "fault_category": "remote-not-working", + "title": "ecobee alerts: settings the installer chose, reported back as problems", + "meaning": "A large share of ecobee alerts report that a configured threshold was reached, not that equipment failed. Compressor lockout temperatures, staging differentials, and reminder intervals are all settings somebody chose during installation, and a thermostat behaving strictly according to them can look like a fault to whoever lives with it.", + "scope_note": "ecobee models differ in which settings they expose and under what names, and some are reachable only through installer settings rather than the everyday menus. The ecobee support material for your model is the reference for which threshold a given alert belongs to and where it is changed.", + "owner_safe_checks": "Read the full alert text rather than acting on its presence, since threshold and reminder alerts state what they are. | Record the outdoor temperature whenever auxiliary or emergency heat engages, so it can be compared against the configured lockout. | Note whether the alert began after a thermostat installation, an equipment change, or a service visit.", + "call_a_technician_when": "Installer settings govern how equipment stages and when it is locked out, and changing them without knowing the equipment can leave a heat pump running outside its intended envelope. | Alerts describing a sensor, a remote sensor link, or equipment that did not respond are measured conditions and need a technician rather than a setting change.", + "reset_guidance": "Dismissing an alert removes the message and leaves the setting that produced it in place. Where the alert describes a threshold, the fix is a configuration change rather than a reset.", + "evidence_class": "oem-operation-manual", + "evidence_publishers": "ecobee", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/ecobee/threshold-and-staging-alerts/" + }, + { + "id": "brands/friedrich/floating-air-fault-indications", + "brand": "Friedrich", + "brand_slug": "friedrich", + "error_code": "Display indications", + "equipment_type": "ductless-mini-split", + "product_family": "Friedrich Floating Air ductless indoor units documented in the Friedrich product resource library", + "models": "Floating Air Premier; Floating Air Pro; Floating Air Select", + "fault_category": "remote-not-working", + "title": "Friedrich Floating Air: reading the display before reaching for a chart", + "meaning": "A Friedrich Floating Air indoor unit uses one small display for three different jobs: reporting status, echoing a setting you have just changed, and reporting a fault. Characters that look alarming are frequently a mode indication or a confirmation, and separating the three is the first step rather than an afterthought.", + "scope_note": "The Floating Air range spans several generations with different displays and different capabilities, including models with and without built-in wireless control. The operation manual issued with your indoor unit is what maps a character to a meaning, and a chart written for another generation can be wrong.", + "owner_safe_checks": "Establish whether the unit still cools or heats when asked, since that alone separates most indications from genuine faults. | Press a remote button and watch whether the display changes and then reverts, which identifies a settings echo. | Photograph any persistent indication before interrupting power, and copy both model numbers from the data plates.", + "call_a_technician_when": "A persistent indication with operation stopped needs the indoor casing opened for testing, which is qualified work on this equipment. | Do not remove the front panel beyond the filter access the manual describes, since the same enclosure carries the supply to the board and the fan.", + "reset_guidance": "A power interruption clears mode and echo indications immediately and leaves a genuine fault report in place, which makes it a useful test as well as a reset. Photograph the display first.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Friedrich", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/friedrich/floating-air-fault-indications/" + }, + { + "id": "brands/fujitsu/operation-and-timer-lamp-blink-codes", + "brand": "Fujitsu General", + "brand_slug": "fujitsu", + "error_code": "Lamp blink pattern", + "equipment_type": "ductless-mini-split", + "product_family": "Fujitsu General residential indoor units that report faults through operation and timer indicator lamps", + "models": "Fujitsu RLS3 wall units; Fujitsu LZAS wall units; Fujitsu ARU ducted indoor units", + "fault_category": "communication-fault", + "title": "Fujitsu blink codes: counting two lamps instead of one", + "meaning": "Fujitsu indoor units without a character display report faults by blinking two indicator lamps in a coordinated pattern. The operation lamp and the timer lamp each carry a count, and the fault is identified by the pair rather than by either one, which is why counting only the light that first catches your eye produces the wrong code.", + "scope_note": "This convention belongs to Fujitsu General residential indoor units that use indicator lamps rather than a numeric display. Fujitsu equipment with a wired controller shows codes directly, and the lamp tables differ between indoor generations, so the operation manual for your own model is the reference.", + "owner_safe_checks": "Film the lamp pattern on a phone through at least three full repetitions before interrupting power for any reason. | Count each lamp separately from the recording and write both numbers down with the date. | Confirm whether the unit still acknowledges commands from the remote control.", + "call_a_technician_when": "Interpreting the pair against the service tables, testing sensing elements, and checking the interconnecting cable require the casing to be opened by a qualified technician. | An outdoor protection reported through the indoor lamps involves the refrigerant circuit, which is certified work rather than an owner check.", + "reset_guidance": "Interrupting power stops the pattern and can clear what the unit was reporting, so capture the recording first. One restart afterwards shows whether the same pattern returns.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Fujitsu General", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/fujitsu/operation-and-timer-lamp-blink-codes/" + }, + { + "id": "brands/ge-appliances/zoneline-ptac-fault-indications", + "brand": "GE Appliances", + "brand_slug": "ge-appliances", + "error_code": "Zoneline fault indications", + "equipment_type": "ductless-mini-split", + "product_family": "GE Zoneline packaged terminal air conditioners and heat pumps documented in GE Appliances owner and support material", + "models": "Zoneline AZ45; Zoneline AZ65; Zoneline AZHS heat pump models", + "fault_category": "not-turning-on", + "title": "GE Zoneline faults: a PTAC is one box with everything in it", + "meaning": "A GE Zoneline is a packaged terminal unit, meaning the compressor, both coils, the fans, and the controls all sit in one chassis through the wall. That changes how a fault reads: there is no interconnecting cable to suspect, no separate outdoor unit to check, and every component behind a code is inside one sleeve.", + "scope_note": "Zoneline covers cooling-only and heat pump models across several generations, with different control boards and different indications. GE Appliances publishes owner and support material per model, and the code or indication on your unit is read against that rather than against a general PTAC chart.", + "owner_safe_checks": "Remove, clean, and refit the filter according to the owner manual, letting it dry fully before it goes back. | Look at the exterior grille and clear obstructions that can be reached without removing it. | Note whether other units in the same building are behaving the same way, and how many.", + "call_a_technician_when": "Withdrawing a chassis from its wall sleeve, testing the control board, and any refrigerant work are service tasks on this equipment. | A packaged unit carries mains supply and a sealed refrigerant circuit inside the same chassis as the filter access, so the boundary for owner work is the filter and the front panel.", + "reset_guidance": "Power interruption clears an indication and the unit re-tests its conditions on restart. Where airflow or charge is behind the fault, the indication returns as soon as the unit works hard enough to meet the same limit.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "GE Appliances", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/ge-appliances/zoneline-ptac-fault-indications/" + }, { "id": "brands/goodman/gmvc-one-flash-lockout", "brand": "Goodman", @@ -523,6 +1063,26 @@ "last_reviewed": "2026-09-03", "reference_url": "https://hvac-bench.com/brands/goodman/gmvc-one-flash-lockout/" }, + { + "id": "brands/goodman/furnace-two-flashes-pressure-switch-closed", + "brand": "Goodman", + "brand_slug": "goodman", + "error_code": "2 flashes", + "equipment_type": "furnace", + "product_family": "Goodman GMVC-series two-stage variable-speed gas furnaces documented in the installation and operating instructions", + "models": "GMVC80; GMVC95; GMVC96", + "fault_category": "pressure-switch-fault", + "title": "Goodman two flashes: the pressure switch is closed when it should be open", + "meaning": "Two flashes on a Goodman integrated control reports the pressure switch circuit closed at a point in the sequence where the control expects it open. The control checks the switch before the inducer runs, and a circuit already made at that moment means the switch cannot prove anything about draft once the inducer starts.", + "scope_note": "Take this from the diagnostic table printed in the Goodman GMVC-series installation and operating instructions. Goodman has used other flash counts on earlier and later control platforms, and Amana equipment built on related controls publishes its own table. Take the count from the label inside your own furnace door.", + "owner_safe_checks": "Read the flash count through the door sight glass rather than removing the blower door, since opening it can cut control power and clear the code. | Confirm the thermostat is set to heat, is calling, and has good batteries if it uses them. | Look for standing water or staining around the base of the furnace and note anything you find without touching tubing or switches.", + "call_a_technician_when": "Testing a pressure switch, clearing condensate tubing, and inspecting the inducer and vent path are licensed gas-furnace tasks. | Never bridge, jumper, or bypass a pressure switch to make a furnace run. The switch is the only thing confirming that combustion products are leaving the building.", + "reset_guidance": "Cutting power clears the stored code, and the control repeats the same pre-start check on the next call for heat. A code that returns immediately is reporting a switch state that has not changed.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Goodman", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/goodman/furnace-two-flashes-pressure-switch-closed/" + }, { "id": "brands/goodman/gmvc80-three-flashes-pressure-switch-open", "brand": "Goodman", @@ -563,6 +1123,46 @@ "last_reviewed": "2026-09-09", "reference_url": "https://hvac-bench.com/brands/goodman/furnace-four-flashes-open-limit/" }, + { + "id": "brands/goodman/furnace-five-flashes-flame-out-of-sequence", + "brand": "Goodman", + "brand_slug": "goodman", + "error_code": "5 flashes", + "equipment_type": "furnace", + "product_family": "Goodman GMVC-series two-stage variable-speed gas furnaces documented in the installation and operating instructions", + "models": "GMVC80; GMVC95; GMVC96", + "fault_category": "flame-out-of-sequence", + "title": "Goodman five flashes: flame sensed when no flame should exist", + "meaning": "Five flashes on a Goodman integrated control reports flame sensed when there was no call for heat and the gas valve should have been closed. The control is describing gas burning outside the sequence it commanded, which is why the response is to shut down and involve a licensed engineer rather than to reset and observe.", + "scope_note": "What follows is scoped to GMVC-series equipment and the flash table Goodman prints for it. Other Goodman control generations, and related brands built on similar boards, assign this count differently, so the diagnostic label fixed inside your own furnace door is the authority rather than any chart found elsewhere.", + "owner_safe_checks": "Check for any smell of gas indoors, and if one is present leave the property and use the emergency number your gas supplier publishes before doing anything else. | Switch the furnace off at its dedicated service switch so the control stops attempting cycles. | Note whether you actually saw or heard burner activity, or whether only the code was present, and record the time.", + "call_a_technician_when": "A gas valve that does not seat, a burner alight outside its commanded sequence, and flame sensing circuit faults are licensed gas engineering work without exception. | Do not operate, reset, or test the furnace to see whether the code returns. The condition being reported is combustion the control did not ask for.", + "reset_guidance": "", + "evidence_class": "oem-service-manual", + "evidence_publishers": "Goodman", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/goodman/furnace-five-flashes-flame-out-of-sequence/" + }, + { + "id": "brands/goodman/furnace-six-flashes-rollout-or-polarity", + "brand": "Goodman", + "brand_slug": "goodman", + "error_code": "6 flashes", + "equipment_type": "furnace", + "product_family": "Goodman GMVC-series and related integrated furnace controls documented in the installation and operating instructions", + "models": "GMVC80; GMVC95; GMVC96; AVPVC air handler controls", + "fault_category": "limit-circuit-lockout", + "title": "Goodman six flashes: a rollout trip and a wiring fault on one count", + "meaning": "Six flashes is a count that Goodman has assigned differently on different integrated controls, including a flame rollout trip on some and a line voltage polarity or grounding condition on others. Because those two readings have completely different risk levels, the diagnostic label inside your own furnace door decides which one applies, not a chart found elsewhere.", + "scope_note": "Goodman publishes the flash-count table on the wiring and diagnostic label of each furnace and in that model's installation and operating instructions. The count-to-meaning mapping is a property of the control platform, so a table from a different Goodman generation, or from Amana equipment on a related control, can be wrong for your furnace.", + "owner_safe_checks": "Read the diagnostic label inside the furnace door through the sight glass or during a permitted access, and record what six flashes is assigned to on that control. | Look and smell for soot, scorching, or combustion odours around the furnace without opening the burner compartment. | List any electrical work, supply changes, or generator use in the period before the code appeared.", + "call_a_technician_when": "A flame rollout trip requires combustion, heat exchanger, and venting assessment by a licensed gas engineer, and the reset button on a rollout device is not an owner control. | Correcting line voltage polarity or a grounding fault at the furnace supply is electrical work for a qualified person, not a matter of swapping conductors on a guess.", + "reset_guidance": "Where the count corresponds to a rollout trip, there is no owner reset: the device exists to stay open until the cause is found. Where it corresponds to a polarity or grounding condition, nothing clears until the supply is corrected.", + "evidence_class": "oem-service-manual", + "evidence_publishers": "Goodman", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/goodman/furnace-six-flashes-rollout-or-polarity/" + }, { "id": "brands/goodman/furnace-seven-flashes-low-flame-signal", "brand": "Goodman", @@ -603,6 +1203,26 @@ "last_reviewed": "2026-09-04", "reference_url": "https://hvac-bench.com/brands/goodman/comfortnet-eb0-eb1-eb3-in-cooling/" }, + { + "id": "brands/nest/delayed-message-and-power", + "brand": "Google Nest", + "brand_slug": "nest", + "error_code": "Delayed", + "equipment_type": "controls-thermostats", + "product_family": "Google Nest learning and programmable thermostats that report power and delay conditions on screen", + "models": "Nest Learning Thermostat; Nest Thermostat E; Nest Thermostat", + "fault_category": "communication-fault", + "title": "Nest delayed messages: the thermostat is rationing its own battery", + "meaning": "A Nest thermostat that says heating or cooling is delayed has detected that its internal battery is low and is postponing the call while it charges. Nothing needs to be wrong with the heating system at all. The thermostat is protecting its own ability to keep running, and the question worth asking is why it is not charging.", + "scope_note": "This covers Google Nest thermostats that draw charge from the heating system wiring. Behaviour differs between Nest generations and between installations with and without a dedicated common conductor, so the Google support material for your specific model is the reference.", + "owner_safe_checks": "Note how often the delay message appears and whether it is worse in cold weather when the heating runs more. | Confirm that the heating itself works once the delay expires, which separates the control from the appliance. | Check whether a battery or power message has appeared alongside the delay at any point.", + "call_a_technician_when": "Running a new conductor to the thermostat position, or altering connections at a Heat Link or equipment terminal, is electrical work for a qualified person. | Do not add a conductor at the equipment end without knowing what it lands on. Heating control wiring carries mains voltage on many United Kingdom installations.", + "reset_guidance": "Restarting the thermostat clears the message and does nothing for the charge that produced it. Where the arrangement cannot keep up, the message returns as soon as the heating is used again.", + "evidence_class": "oem-support", + "evidence_publishers": "Google Nest", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/nest/delayed-message-and-power/" + }, { "id": "brands/nest/e73-no-power-rc", "brand": "Google Nest", @@ -643,6 +1263,26 @@ "last_reviewed": "2026-09-03", "reference_url": "https://hvac-bench.com/brands/nest/e74-no-power-rh/" }, + { + "id": "brands/grant/aerona-alarm-handling", + "brand": "Grant", + "brand_slug": "grant", + "error_code": "Aerona alarm codes", + "equipment_type": "heat-pump", + "product_family": "Grant Aerona air source heat pumps documented in the Grant fault and support material", + "models": "Aerona3; Aerona 290; Aerona R32 range", + "fault_category": "protection-shutdown", + "title": "Grant Aerona alarms: a heat pump in a house built for a boiler", + "meaning": "Grant Aerona alarms divide between the sealed refrigerant side of the heat pump and the water circuit it serves, and the second group is where most retrofit installations end up. A heat pump moves far more water than the boiler it replaced, so a circuit that was adequate before can leave the appliance short of flow.", + "scope_note": "The Aerona name covers several generations with different refrigerants and different controllers, and the alarm set differs between them. Take the model and serial number from the outdoor unit and read the alarm against Grant documentation for that unit rather than a general heat pump list.", + "owner_safe_checks": "Photograph the controller showing the alarm before anybody clears it, together with any text alongside the number. | Write down how cold it was outdoors and what flow temperature the controller had been calling for when the alarm arrived. | Feel every radiator and underfloor manifold during a heating period and map which heat well and which do not.", + "call_a_technician_when": "Where an alarm sits on the sealed side of the machine, only a certified person may open it: the F-Gas framework governs that in Britain and the European Union, and Section 608 does the equivalent job in the United States. | Adjusting pump settings, balancing a circuit, or altering emitters on a heat pump installation should be done by somebody working to heat pump flow rates rather than boiler practice.", + "reset_guidance": "Expect the system to run again once an alarm is cleared, and to keep running until the weather asks for the same output. What identifies a marginal circuit is the shape of a whole winter, so keep a note of every occurrence rather than the most recent one.", + "evidence_class": "oem-support", + "evidence_publishers": "Grant UK", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/grant/aerona-alarm-handling/" + }, { "id": "brands/gree/e5-overcurrent-low-voltage", "brand": "Gree", @@ -703,6 +1343,46 @@ "last_reviewed": "2026-09-03", "reference_url": "https://hvac-bench.com/brands/gree/e7-error-code/" }, + { + "id": "brands/gree/f1-indoor-ambient-sensor", + "brand": "Gree", + "brand_slug": "gree", + "error_code": "F1", + "equipment_type": "ductless-mini-split", + "product_family": "Gree residential mini-split indoor units using the F-series sensing bulb codes described in Gree North America support", + "models": "Gree Livo wall units; Gree Vireo wall units; Gree Sapphire wall units; Multi21 indoor units", + "fault_category": "temperature-sensor-fault", + "title": "Gree F1: the indoor ambient sensing bulb is open or shorted", + "meaning": "Gree assigns F1 to the indoor ambient temperature sensing bulb being open or short circuited. That bulb reads the air entering the indoor unit, which the system treats as the room temperature, so once the reading leaves its acceptable range the control has no reference against which to compare the set point.", + "scope_note": "Gree publishes the F-series sensing entries for its residential mini-split range. Gree also manufactures under other brand names, and a unit sold under a partner brand may present a different code set even where the hardware is related. Check the code against the manual supplied with your own indoor unit.", + "owner_safe_checks": "Read the two characters carefully and confirm it is F1 rather than F2 or another F-series entry, since the digit selects the sensor. | Compare the temperature the indoor unit reports with a thermometer placed near the intake, and record both. | Make sure nothing was left half-fitted after the last clean, particularly the front panel latch and the filter frames.", + "call_a_technician_when": "Gree places sensing bulb faults among the categories requiring a licensed technician, and the components sit inside the indoor casing. | Do not open the indoor unit to inspect or reseat a sensor connector. The same enclosure carries the supply to the board and the fan motor.", + "reset_guidance": "Killing the supply blanks the display for a moment, then the board takes the same measurement again as soon as it wakes. An F1 that comes straight back is describing a resistance that never moved.", + "evidence_class": "oem-support", + "evidence_publishers": "Gree Comfort", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/gree/f1-indoor-ambient-sensor/" + }, + { + "id": "brands/gree/f2-evaporator-sensing-bulb", + "brand": "Gree", + "brand_slug": "gree", + "error_code": "F2", + "equipment_type": "ductless-mini-split", + "product_family": "Gree residential mini-split indoor units using the F-series sensing bulb codes described in Gree North America support", + "models": "Gree Livo wall units; Gree Vireo wall units; Multi21 indoor units; Gree cassette indoor units", + "fault_category": "temperature-sensor-fault", + "title": "Gree F2: losing the coil sensor removes the freeze protection", + "meaning": "Gree assigns F2 to the indoor evaporator sensing bulb being open or short circuited. That bulb sits on the indoor coil rather than in the air stream, and its reading is what freeze protection and cold-draught prevention are built on, so the unit stops rather than run those functions without a value it can trust.", + "scope_note": "The F-series entries described here belong to Gree residential mini-split equipment. Equipment manufactured by Gree and sold under a partner brand can present its own code set and its own sensor arrangement, so match the code to the manual issued with your indoor unit rather than to the manufacturer behind it.", + "owner_safe_checks": "Select fan-only operation if ice is present and let the coil thaw without applying heat, water, or any tool to it. | Photograph any frost or ice before it melts, since the pattern of where it formed is useful to service. | Note whether heating had been slow to blow warm air in the weeks before the code appeared.", + "call_a_technician_when": "A bulb clamped to refrigerant tubing behind the front panel is not owner-accessible, and Gree assigns this class of fault to a licensed technician. | Repeated indoor coil icing needs airflow and refrigerant assessment, which is certified work rather than something to diagnose from the room.", + "reset_guidance": "Clearing the display does not change the resistance at the coil, and the board reads it again immediately. Treat a returning F2 as confirmation that the sensing path is still outside its band.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Gree Comfort", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/gree/f2-evaporator-sensing-bulb/" + }, { "id": "brands/gree/h5-error-code", "brand": "Gree", @@ -723,6 +1403,26 @@ "last_reviewed": "2026-09-02", "reference_url": "https://hvac-bench.com/brands/gree/h5-error-code/" }, + { + "id": "brands/haier/e5-overcurrent-protection", + "brand": "Haier", + "brand_slug": "haier", + "error_code": "E5", + "equipment_type": "ductless-mini-split", + "product_family": "Haier residential split air conditioners documented in the Haier service and resource library", + "models": "Haier Forward series; Haier Flexis series; Haier Pearl series", + "fault_category": "voltage-protection", + "title": "Haier E5: overcurrent stops are as much about the supply as the unit", + "meaning": "Haier uses E5 for an overcurrent condition, meaning the current drawn exceeded what the control permits. Current is a product of the work being demanded and the voltage available to do it, so a low or unstable supply produces the same code as a compressor that is hard to turn.", + "scope_note": "This applies to Haier residential split equipment documented in the Haier service library. Haier manufactures for several brand programmes, and units sold under other names may use a different code set even where hardware overlaps. Confirm against the manual issued with your own unit.", + "owner_safe_checks": "Make one start attempt and note how long the outdoor unit runs before the code returns. | Watch whether household lighting reacts at the moment of start, and note the time of day each occurrence happens. | Confirm no protective device in the consumer unit or panel has operated, and that the unit is on the supply arrangement it was installed with.", + "call_a_technician_when": "Measuring supply voltage under starting load, testing compressor windings, and assessing the drive are energised tasks for a qualified person. | A protective device that trips when the unit starts, a burning smell, or heat at an isolator means leaving the supply off and arranging an electrical inspection before anything else.", + "reset_guidance": "Allow yourself a single attempt and then stop. Everything after the first try simply re-runs the surge that tripped the protection, and none of those attempts tells you anything the first one did not.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Haier Appliances", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/haier/e5-overcurrent-protection/" + }, { "id": "brands/haier/forward-series-e7-error", "brand": "Haier", @@ -783,6 +1483,26 @@ "last_reviewed": "2026-09-03", "reference_url": "https://hvac-bench.com/brands/hisense/hi-ultra-xtreme-code-16/" }, + { + "id": "brands/hisense/sensor-error-codes", + "brand": "Hisense", + "brand_slug": "hisense", + "error_code": "Sensor group", + "equipment_type": "ductless-mini-split", + "product_family": "Hisense residential split air conditioners documented in the Hisense service and document library", + "models": "Hisense Hi Ultra; Hisense Hi Ultra Xtreme; Hisense Energy series", + "fault_category": "temperature-sensor-fault", + "title": "Hisense sensor codes: when the number identifies a reading, not a part", + "meaning": "Hisense sensing codes report that a temperature reading has left the range the control will act on. Every one of them describes a measurement rather than a component, which is why the same code covers a failed element, a disconnected plug, and a corroded terminal without distinguishing between them.", + "scope_note": "Hisense publishes documentation by product family rather than as one brand-wide list, and code assignments differ between the residential ranges. The service document for the model on your data plate is the reference; a table gathered from another Hisense product may not transfer.", + "owner_safe_checks": "Photograph the indoor display showing the code before interrupting power for any reason. | Compare the temperature the unit reports with a thermometer and write both figures down. | Note any storm, flooding, pest activity, or outdoor work in the weeks before the fault appeared.", + "call_a_technician_when": "Measuring sensing resistance and inspecting connectors requires the indoor or outdoor casing to be opened, and the outdoor enclosure carries mains voltage as well as refrigerant pipework. | Do not attempt to dry, clean, or reseat an outdoor connector. Water ingress often accompanies damage that is not visible from outside the casing.", + "reset_guidance": "The measurement is taken again as soon as the equipment powers up, so a reset changes nothing while the reading is out of range. It does, however, erase the displayed code, so photograph it first.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Hisense HVAC", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/hisense/sensor-error-codes/" + }, { "id": "brands/hitachi/yutaki-alarm-70", "brand": "Hitachi", @@ -823,6 +1543,66 @@ "last_reviewed": "2026-09-03", "reference_url": "https://hvac-bench.com/brands/hitachi/yutaki-alarm-77-78/" }, + { + "id": "brands/hitachi/yutaki-alarm-code-groups", + "brand": "Hitachi", + "brand_slug": "hitachi", + "error_code": "Alarm groups", + "equipment_type": "heat-pump", + "product_family": "Hitachi Yutaki air-to-water heat pump systems documented in the Hitachi air-to-water installation and operation manuals", + "models": "Yutaki S; Yutaki S Combi; Yutaki M; Yutaki S80", + "fault_category": "protection-shutdown", + "title": "Hitachi Yutaki alarms: the water side and the refrigerant side are different jobs", + "meaning": "A Yutaki system has two fluid circuits that can each raise alarms: a refrigerant circuit between the outdoor unit and the heat exchanger, and a water circuit serving the house. Knowing which side an alarm belongs to decides almost everything that follows, including whether the work is certified refrigerant handling or ordinary heating pipework.", + "scope_note": "Yutaki covers split, monobloc, and high-temperature configurations, and the alarm set differs between them as well as between generations of the controller. Read the alarm against the installation and operation manual for your exact configuration rather than a general Hitachi list.", + "owner_safe_checks": "Photograph the controller showing the alarm number and any accompanying text before anyone resets it. | Record the outdoor temperature, the flow temperature the controller was asking for, and whether hot water is also affected. | Check the system pressure on the heating circuit and note the reading while the system is cold.", + "call_a_technician_when": "Any alarm belonging to the refrigerant circuit requires a certified refrigerant handler under F-Gas rules in the United Kingdom and European Union, or EPA Section 608 in the United States. | Water-side work on a heat pump, including pump settings and circuit balancing, should be carried out by an engineer familiar with heat pump flow rates rather than boiler practice.", + "reset_guidance": "Clearing an alarm allows the system to try again, and where the condition is seasonal it may run for days before repeating. Record the alarm and the conditions before resetting, since the pattern is what identifies a marginal design.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Hitachi Cooling and Heating", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/hitachi/yutaki-alarm-code-groups/" + }, + { + "id": "brands/hive/boiler-not-responding-to-hive", + "brand": "Hive", + "brand_slug": "hive", + "error_code": "No signal / offline", + "equipment_type": "controls-thermostats", + "product_family": "Hive heating control systems using a hub, a thermostat, and a boiler receiver as described in Hive support", + "models": "Hive Active Heating; Hive Thermostat Mini; Hive Hub and receiver", + "fault_category": "communication-fault", + "title": "Hive not controlling the boiler: three links that can break separately", + "meaning": "A Hive installation is a chain: the app talks to Hive, Hive talks to the hub, the hub talks to the thermostat and the receiver, and the receiver switches the boiler. A break anywhere along that chain presents in the app as the heating not responding, and the repair depends entirely on where the break is.", + "scope_note": "Hive has shipped several generations of hub, thermostat, and receiver with different radio arrangements and different indications. The Hive support material for the products you actually own is the reference, and the position of a break is established from the devices rather than from the app alone.", + "owner_safe_checks": "Operate the manual or boost control on the receiver and note whether the boiler responds, which splits the fault in half immediately. | Check whether the thermostat still controls the heating locally even if the app cannot reach the system. | Note anything that changed in the house recently: a new router, a moved hub, an appliance, or building work.", + "call_a_technician_when": "Wiring between a receiver and a heating appliance carries mains voltage on United Kingdom installations and is not an owner task. | A boiler that does not respond to manual operation at the receiver is a heating fault rather than a connectivity one, and it belongs to a Gas Safe registered engineer.", + "reset_guidance": "Restarting the hub and the router restores an internet or account link and does nothing for a radio or wiring break. Establish where the break is with the receiver test before restarting anything.", + "evidence_class": "oem-support", + "evidence_publishers": "Hive Home; Hive", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/hive/boiler-not-responding-to-hive/" + }, + { + "id": "brands/honeywell-home/t6-not-calling-for-heat", + "brand": "Honeywell Home", + "brand_slug": "honeywell-home", + "error_code": "No heat demand", + "equipment_type": "controls-thermostats", + "product_family": "Honeywell Home T6 programmable thermostats configured through installer setup parameters", + "models": "T6 Pro; T6 Pro Smart; Lyric T6; T6R wireless", + "fault_category": "communication-fault", + "title": "Honeywell T6 not calling for heat: installer settings before faults", + "meaning": "A Honeywell T6 that shows a set point above the room temperature and still produces no heat is either being prevented by a configuration parameter or is not connected to what it thinks it is. Installer setup decides system type, staging, changeover, and minimum off times, and each of those can suppress a demand that looks perfectly reasonable on screen.", + "scope_note": "T6 covers wired and wireless variants across several markets, with installer setup parameters that differ between them. The installer setup guide for the exact T6 variant you own is the reference, and a parameter number from a different variant can select something else entirely.", + "owner_safe_checks": "Confirm the time, the day, and the schedule on the thermostat, and check whether a hold or a temporary override is active. | Raise the set point by hand and note whether heat arrives, which separates scheduling from everything downstream. | On a wireless variant, look at the receiver near the appliance and note whether it indicates a demand.", + "call_a_technician_when": "Installer setup parameters govern which terminals are energised and how equipment is staged, and selecting the wrong system type can make a thermostat energise a circuit the equipment does not expect. | Terminals inside a boiler or a wireless receiver sit at mains potential in British installations, which puts any work on them outside what an occupant should attempt.", + "reset_guidance": "Restarting the thermostat clears a temporary state and leaves installer parameters exactly as they were. Where configuration is the cause, only the setup menu changes it.", + "evidence_class": "oem-operation-manual", + "evidence_publishers": "Honeywell Home", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/honeywell-home/t6-not-calling-for-heat/" + }, { "id": "brands/ideal-heating/logic-f1-low-pressure", "brand": "Ideal Heating", @@ -843,6 +1623,26 @@ "last_reviewed": "2026-09-09", "reference_url": "https://hvac-bench.com/brands/ideal-heating/logic-f1-low-pressure/" }, + { + "id": "brands/ideal-heating/logic-f2-flame-loss", + "brand": "Ideal Heating", + "brand_slug": "ideal-heating", + "error_code": "F2", + "equipment_type": "boiler", + "product_family": "Ideal Logic and Vogue gas boilers using the F-series and L-series fault codes published by Ideal Heating", + "models": "Logic Combi; Logic Max Combi; Logic System; Vogue Max", + "fault_category": "flame-loss", + "title": "Ideal F2: the flame was there and then it was not", + "meaning": "Ideal uses F2 for a flame loss condition, which is a different event from a failure to establish flame at all. The burner lit, ran, and then the appliance stopped detecting combustion, so the investigation starts from what changed during operation rather than from what prevented ignition.", + "scope_note": "Ideal publishes separate fault code lists for its Logic, Logic Max, and Vogue ranges, and the same character can carry different detail across them. Take the code from the display of the appliance in front of you and check it against the Ideal literature for that model rather than a general list.", + "owner_safe_checks": "Time how long the boiler runs before the fault appears, and note whether heating or hot water was actually produced. | Record which other gas appliances were in use each time the fault occurred. | Note whether failures happen on small demands, large demands, or both, since the pattern is diagnostic.", + "call_a_technician_when": "Measuring working gas pressure, testing the flame signal, and inspecting the flue and condensate arrangement are Gas Safe registered tasks. | If gas can be smelled, that single fact outranks the fault code entirely. Get everyone out, touch no switches, and telephone the emergency line for your supplier once you are outside.", + "reset_guidance": "Ideal permits a reset from the control panel, and a small number of attempts establish whether the fault repeats and at what point. Continuing beyond that adds ignition cycles without adding information.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Ideal Heating", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/ideal-heating/logic-f2-flame-loss/" + }, { "id": "brands/ideal-heating/logic-l1-and-l3-water-flow", "brand": "Ideal Heating", @@ -903,6 +1703,26 @@ "last_reviewed": "2026-09-03", "reference_url": "https://hvac-bench.com/brands/klimaire/ksiv-e1-error-code/" }, + { + "id": "brands/klimaire/indoor-and-outdoor-code-split", + "brand": "Klimaire", + "brand_slug": "klimaire", + "error_code": "Indoor and outdoor groups", + "equipment_type": "ductless-mini-split", + "product_family": "Klimaire ductless mini-split systems documented in the Klimaire service and support library", + "models": "KSIV series; KSIO series; Klimaire multi-zone indoor units", + "fault_category": "communication-fault", + "title": "Klimaire codes: which half of the system is speaking", + "meaning": "Klimaire documents its codes in groups that separate indoor conditions from outdoor ones, and that split is the first thing to use. Knowing which half raised the condition tells you where a technician will work and what class of repair is likely, before any exact entry has been found.", + "scope_note": "Klimaire publishes service documentation per series, and the KSIV and KSIO lines carry their own tables. The document matching the model number on the data plate is the mapping, and a chart labelled with the brand alone can describe a different series.", + "owner_safe_checks": "Photograph the displayed code and both data plates before contacting anybody or interrupting power. | Note whether the outdoor unit runs at all, which is observable from a safe distance and separates the two groups immediately. | Record whether the fault has been present since installation or developed after a period of normal service.", + "call_a_technician_when": "Outdoor-side conditions involve the sealed refrigerant circuit and the drive, both of which require certification and the appropriate instruments. | Indoor casings carry the supply to the board and the fan motor, so opening one is qualified work even where the component behind the code is small.", + "reset_guidance": "A single power interruption separates a latched report from a live condition, and on this equipment it also tells you whether the outdoor unit attempts to start. Capture the code before doing it.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Klimaire", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/klimaire/indoor-and-outdoor-code-split/" + }, { "id": "brands/klimaire/p4-inverter-drive-error", "brand": "Klimaire", @@ -983,6 +1803,46 @@ "last_reviewed": "2026-09-03", "reference_url": "https://hvac-bench.com/brands/lennox/xp17-alert-418-419/" }, + { + "id": "brands/lennox/icomfort-control-restarting", + "brand": "Lennox", + "brand_slug": "lennox", + "error_code": "Control restart", + "equipment_type": "controls-thermostats", + "product_family": "Lennox iComfort communicating thermostats and the equipment controls they are paired with", + "models": "iComfort S30; iComfort E30; iComfort M30; iComfort Wi-Fi", + "fault_category": "communication-fault", + "title": "Lennox iComfort keeps restarting: separating a control reboot from an equipment fault", + "meaning": "A Lennox iComfort control that restarts on its own is describing its own operating conditions rather than a heating or cooling fault. What the control needs is a stable supply from the equipment to stay running, and a supply that dips, a loose conductor, or a software condition can all produce a reboot that looks alarming and means something specific.", + "scope_note": "This covers Lennox iComfort communicating controls paired with compatible Lennox equipment. A Lennox system using a conventional thermostat behaves differently, and a restart on a non-Lennox control fitted to Lennox equipment is outside what Lennox documents. Identify the control model from its own settings menu.", + "owner_safe_checks": "Keep a short log of each restart with the time and what the heating or cooling system was doing in that moment. | Note which settings survive a restart and which have to be entered again. | Check whether any recent electrical work, network change, or equipment service preceded the behaviour.", + "call_a_technician_when": "Inspecting control wiring at the equipment, measuring supply under load, and updating control firmware are dealer tasks on a communicating system. | Do not add or move conductors at the control or the equipment to try to stabilise the supply. Communicating systems use those conductors for data as well as power.", + "reset_guidance": "The control restarting is itself a reset, so performing another one adds nothing. What matters is whether the restarts are synchronised with equipment starting, which only observation over time can establish.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Lennox", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/lennox/icomfort-control-restarting/" + }, + { + "id": "brands/lg/ch01-ch02-ch06-ch12-sensor-codes", + "brand": "LG", + "brand_slug": "lg", + "error_code": "CH01 / CH02 / CH06 / CH12", + "equipment_type": "ductless-mini-split", + "product_family": "LG residential air conditioners covered by the United States help-library article that groups these codes as sensor problems", + "models": "LG single-split wall units; LG multi-split indoor units; LG art cool wall units", + "fault_category": "temperature-sensor-fault", + "title": "LG CH01, CH02, CH06 and CH12: the codes LG calls a sensor problem", + "meaning": "LG's own help-library article does not give these codes one meaning each. It places CH01, CH02, CH06, CH12, the CH41 to CH48 range, E1 to E3, E7, E8, F2 and F3 in a single category described as a problem with a sensor. The practical consequence is that the code identifies which sensing input is unhappy, while LG's published customer guidance stops at the category.", + "scope_note": "The grouping quoted here is LG's United States help-library guidance for residential air conditioners. LG multi-split and commercial equipment publish fuller per-code tables in their service literature, and LG documentation varies by region and by generation, so a code on a commercial LG system is read from that system's own manual.", + "owner_safe_checks": "Write the code down exactly as shown, since a zero and a letter O are easy to confuse on a small indoor display. | Carry out the single power interruption LG describes, at the plug or the breaker, and wait about five minutes before restoring supply. | Compare the displayed room temperature with a separate thermometer and record both figures before the reset.", + "call_a_technician_when": "LG instructs the owner not to disassemble the air conditioner or replace internal parts, and warns that doing so may cause fire, electric shock, or serious injury. | If the same code appears again after one reset, LG's stated instruction is to stop using the product and request service to prevent further damage.", + "reset_guidance": "LG permits exactly one interruption of about five minutes at the plug or the breaker. Repeating it after the code returns is contrary to LG's own published instruction to stop using the product.", + "evidence_class": "oem-support", + "evidence_publishers": "LG Electronics", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/lg/ch01-ch02-ch06-ch12-sensor-codes/" + }, { "id": "brands/lg/ch04-error-code", "brand": "LG", @@ -1043,6 +1903,46 @@ "last_reviewed": "2026-09-09", "reference_url": "https://hvac-bench.com/brands/lg/ch07-operating-mode-conflict/" }, + { + "id": "brands/lg/ch21-ch23-ch26-ch29-compressor-codes", + "brand": "LG", + "brand_slug": "lg", + "error_code": "CH21 / CH23 / CH26 / CH29", + "equipment_type": "heat-pump", + "product_family": "LG residential air conditioners covered by the United States help-library article grouping these codes as outdoor compressor or circuit board problems", + "models": "LG single-split outdoor units; LG multi-split outdoor units; LG inverter heat pump outdoor units", + "fault_category": "inverter-module-protection", + "title": "LG CH21, CH23, CH26 and CH29: the outdoor compressor and board group", + "meaning": "LG's help-library article assigns CH21, CH23, CH26, CH29 and E9 to a single category: a problem with the outdoor unit compressor or circuit board. That is a narrower statement than it appears, because it moves the fault out of the indoor unit and out of the sensing group and places it in the inverter drive and compressor side of the system.", + "scope_note": "What is quoted below is the category LG gives home customers in its United States help library, and nothing finer. LG service literature publishes fuller definitions for each of these codes, and the meaning of a CH number on LG commercial or variable refrigerant flow equipment is taken from that product's own manual rather than from this article.", + "owner_safe_checks": "Make one start attempt after LG's five-minute power interruption, and count how many seconds the outdoor unit runs before it stops. | Observe whether the outdoor fan turns at all during the attempt, from a safe distance and without touching the guard. | See whether a breaker or fuse serving the outdoor unit has tripped, and whether anything else in the property is misbehaving at the same time.", + "call_a_technician_when": "LG instructs the owner not to disassemble the unit or replace internal parts, warning of fire, electric shock, serious injury, or death. | Measuring compressor windings, inverter output, and supply voltage under load are energised tasks inside the outdoor enclosure and belong to a qualified engineer.", + "reset_guidance": "One interruption of about five minutes is what LG publishes. Because this group covers an electrical protection, repeating it after the code returns risks converting a diagnosable fault into a replacement.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "LG Electronics", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/lg/ch21-ch23-ch26-ch29-compressor-codes/" + }, + { + "id": "brands/lg/multi-split-mode-conflict", + "brand": "LG", + "brand_slug": "lg", + "error_code": "Mode conflict", + "equipment_type": "multi-zone", + "product_family": "LG multi-split systems where several indoor units share a single outdoor unit, as described in LG help-library guidance", + "models": "LG multi-split outdoor units; LG multi-split wall indoor units; LG multi-split ducted indoor units", + "fault_category": "not-heating", + "title": "LG multi-split: one outdoor unit cannot heat and cool at once", + "meaning": "LG states that on a multi-product system every indoor unit connected to one outdoor unit has to run in cooling only or in heating only. Cooling and dehumidification cannot run at the same time as heating, while air purification and fan modes are unrestricted, so one room set the wrong way stops another from getting what it asked for.", + "scope_note": "This applies to LG multi-split arrangements where several indoor units share one outdoor unit. Heat recovery systems, which are a different architecture, can serve simultaneous heating and cooling, and single-split installations have no conflict to resolve. Confirm how many indoor units your outdoor unit serves.", + "owner_safe_checks": "Walk through every room with an indoor unit and note which mode each one is set to, including any that are switched on but unused. | Switch off indoor units in rooms nobody is using rather than leaving them running in a conflicting mode. | Set every remaining unit explicitly to the same mode rather than relying on automatic selection.", + "call_a_technician_when": "A conflict that persists after every indoor unit is set to the same mode is no longer a mode conflict and needs the system examined. | Changing how a multi-split is configured, including adding or reassigning indoor units, is installer work rather than a settings change.", + "reset_guidance": "Nothing needs resetting for a mode conflict, because nothing has faulted. Operation resumes as soon as the requests agree, which is why setting every unit to one mode is the test as well as the fix.", + "evidence_class": "oem-support", + "evidence_publishers": "LG Electronics", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/lg/multi-split-mode-conflict/" + }, { "id": "brands/midea/e1-error-code", "brand": "Midea", @@ -1083,6 +1983,46 @@ "last_reviewed": "2026-09-09", "reference_url": "https://hvac-bench.com/brands/midea/e2-indoor-coil-sensor/" }, + { + "id": "brands/midea/e3-indoor-fan-speed", + "brand": "Midea", + "brand_slug": "midea", + "error_code": "E3", + "equipment_type": "ductless-mini-split", + "product_family": "Midea residential split air conditioners covered by the Midea online troubleshooting code reference", + "models": "Midea Aurora series; Midea EVOX series; Midea Mission series", + "fault_category": "not-turning-on", + "title": "Midea E3: the indoor fan is not running at the speed it was told to", + "meaning": "Midea's code reference gives E3 as indoor fan speed out of control. The indoor board commands a speed and compares it against the rotation the motor actually reports, and a mismatch beyond what it tolerates raises the code. It says the speed is wrong; it does not say whether the motor, the drive, or something physical caused it.", + "scope_note": "Midea manufactures for many brands as well as selling under its own name, and code sets differ between those programmes even where hardware is shared. This reading applies to Midea-branded residential split equipment covered by the Midea troubleshooting reference. Confirm against the manual issued with your unit.", + "owner_safe_checks": "Switch the unit off rather than leaving it attempting to start, since the refrigerant circuit should not run against a stationary indoor coil. | Clean or replace the indoor filters according to the manual, and confirm the outlet louvres are free to move. | Capture a description of any sound that preceded the fault, which setting produced it, and approximately what week it began.", + "call_a_technician_when": "Everything that would confirm this fault, from releasing a jammed wheel to putting a meter on the feedback line, happens with the indoor casing open and is therefore qualified work. | Do not reach through the outlet louvres to turn the fan wheel. The blades and the drive are not designed for that access and the assembly can start without warning.", + "reset_guidance": "Power interruption clears the display and the board repeats the speed comparison on the next start. A code returning within seconds means the mechanical or electrical condition is unchanged.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Midea", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/midea/e3-indoor-fan-speed/" + }, + { + "id": "brands/midea/p2-compressor-top-temperature", + "brand": "Midea", + "brand_slug": "midea", + "error_code": "P2", + "equipment_type": "heat-pump", + "product_family": "Midea residential split air conditioners and heat pumps covered by the Midea online troubleshooting code reference", + "models": "Midea Aurora series; Midea EVOX series; Midea multi-zone outdoor units", + "fault_category": "protection-shutdown", + "title": "Midea P2: the compressor top temperature protection has acted", + "meaning": "Midea gives P2 as compressor top temperature protection. A sensor on the compressor shell has reported a temperature above what the control permits, and operation has stopped to keep the motor and its lubricant inside their design range. It is a protection acting correctly, not a declaration that the compressor has failed.", + "scope_note": "Midea builds equipment for several brand programmes alongside its own range, and code assignments vary between them. This reading applies to Midea-branded residential split equipment covered by the Midea troubleshooting reference; a P2 on a unit sold under another name follows that brand's documentation.", + "owner_safe_checks": "Stop calling for operation and leave the system off so the compressor is not repeatedly restarted into the same condition. | Isolate the outdoor unit at its dedicated switch, then clear leaves, cuttings, and vegetation from around the casing without touching the coil fins. | Note the outdoor temperature at each stop and how the system had been performing in the weeks before.", + "call_a_technician_when": "Charge measurement, leak detection, coil cleaning, and shell sensor testing are certified refrigerant and electrical tasks. | Never add refrigerant without finding where the previous charge went, and never wash or comb an outdoor coil without the training to avoid damaging the fins.", + "reset_guidance": "The protection re-evaluates the shell temperature on the next run, so a reset changes nothing while the condition persists. Repeated restarts add heat cycles the limit exists to prevent.", + "evidence_class": "oem-support", + "evidence_publishers": "Midea; Midea America", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/midea/p2-compressor-top-temperature/" + }, { "id": "brands/mitsubishi/e6-communication-error", "brand": "Mitsubishi Electric", @@ -1123,6 +2063,66 @@ "last_reviewed": "2026-09-07", "reference_url": "https://hvac-bench.com/brands/mitsubishi/ecodan-l9-flow-rate/" }, + { + "id": "brands/mitsubishi/p1-intake-air-thermistor", + "brand": "Mitsubishi Electric", + "brand_slug": "mitsubishi", + "error_code": "P1", + "equipment_type": "ductless-mini-split", + "product_family": "Mitsubishi Electric indoor units that publish the P-series fault table, covering Mr Slim and M-Series indoor equipment", + "models": "MSZ-GL series; MSZ-FH series; PLA-A series; PKA-A series", + "fault_category": "temperature-sensor-fault", + "title": "Mitsubishi P1: the room sensor the whole control loop depends on", + "meaning": "P1 reports that the indoor intake air thermistor is reading outside the range the control accepts, which the reference describes as an open circuit, a short circuit, or a detached connector. The reading matters because the intake air sensor is what the system calls room temperature, so once it is untrusted the control has no basis for deciding capacity and stops rather than guessing.", + "scope_note": "This reading covers Mitsubishi Electric indoor families that publish the P-series fault table. Mitsubishi Heavy Industries equipment is a separate manufacturer with its own table, and a P1 shown by a third-party controller wired to a Mitsubishi indoor unit is not the same entry. Confirm the indoor model code before acting on it.", + "owner_safe_checks": "Compare the room temperature the controller displays with a separate thermometer placed near the indoor unit intake, and write both values down. | Confirm the front panel and filters are fully seated and closed, since a partly open panel changes what the intake sensor is exposed to. | Record the blink pattern or controller display, the indoor address, and whether the fault follows any recent maintenance.", + "call_a_technician_when": "Measuring thermistor resistance, inspecting board connectors, and replacing a sensor harness require the indoor electrical enclosure to be opened by a qualified technician. | If P1 is accompanied by a burning smell, visible discoloration, or a tripping circuit protective device, isolate the unit and stop using it until it has been inspected.", + "reset_guidance": "Interrupting power clears the display but does not change a resistance that is out of range, so a P1 that returns after one restart is reporting a condition that is still present.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Mitsubishi Electric", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/mitsubishi/p1-intake-air-thermistor/" + }, + { + "id": "brands/mitsubishi/p2-indoor-pipe-thermistor", + "brand": "Mitsubishi Electric", + "brand_slug": "mitsubishi", + "error_code": "P2", + "equipment_type": "ductless-mini-split", + "product_family": "Mitsubishi Electric indoor units publishing the P-series fault table, including M-Series wall units and Mr Slim indoor equipment", + "models": "MSZ-AP series; MSZ-GL series; PLA-A series; PEAD-A series", + "fault_category": "temperature-sensor-fault", + "title": "Mitsubishi P2: the pipe sensor that tells defrost and freeze control what to do", + "meaning": "P2 identifies an abnormality in the indoor pipe temperature thermistor, the sensor clamped to the indoor heat exchanger rather than the one reading room air. Its value drives freeze protection in cooling and heat-exchanger temperature logic in heating, so the control stops rather than run those functions blind.", + "scope_note": "The entry read here belongs to Mitsubishi Electric indoor units that publish the P-series table. Some Mitsubishi indoor units carry more than one pipe thermistor, and the table then separates them by code, so the position of the failed sensor comes from the service manual for that exact indoor model rather than from the code alone.", + "owner_safe_checks": "Switch the affected indoor unit to fan only if the coil has visible frost, and let it thaw without heat, tools, or water. | Note the indoor address, the room, and whether other heads on the same system continue to work normally. | Write down any period in the preceding weeks when heating airflow was slow to start or cooling produced indoor frost.", + "call_a_technician_when": "Verifying sensor mounting, measuring thermistor resistance against the published curve, and inspecting the indoor harness all need the indoor casing opened by a qualified technician. | Repeated indoor coil frosting alongside P2 needs refrigerant and airflow assessment, which is licensed work and not an owner task.", + "reset_guidance": "Power interruption clears the displayed code, but the pipe sensor reading is measured again on the next cycle, so a returning P2 means the resistance or the mounting has not changed.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Mitsubishi Electric", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/mitsubishi/p2-indoor-pipe-thermistor/" + }, + { + "id": "brands/mitsubishi/p5-drain-pump-protection", + "brand": "Mitsubishi Electric", + "brand_slug": "mitsubishi", + "error_code": "P5", + "equipment_type": "ductless-mini-split", + "product_family": "Mitsubishi Electric indoor units that publish the P-series protection table, including Mr Slim cassette, ducted, and ceiling-suspended indoor units", + "models": "PLA-A series cassettes; PEAD-A series ducted indoor units; PCA-A series ceiling suspended indoor units", + "fault_category": "water-leak", + "title": "Mitsubishi P5: the drain protection stopped the unit before water did", + "meaning": "P5 is a drain protection stop on a Mitsubishi Electric indoor unit. The control saw the float switch rise, or it saw the drain pump circuit fail to respond, and it shut cooling down to keep the condensate tray from overflowing. The code proves water did not leave the tray fast enough. It does not name the blockage, the pump, or the switch as the failed part.", + "scope_note": "P5 is read here from the Mitsubishi Electric fault-code reference for the indoor families that publish the P-series table. Wall-mounted units without a condensate pump do not carry the same detection, and a Mitsubishi Electric controller fitted to another manufacturer's indoor unit will not follow this table. Match the code to the indoor unit model on its own rating label rather than to the outdoor unit.", + "owner_safe_checks": "Switch the indoor unit to fan only or off so the coil stops producing condensate, and leave it that way until the fault is assessed. | Look at the visible outdoor end of the condensate line during a period when the unit had been cooling, and note whether any water discharged. | Photograph the controller showing P5 together with the indoor unit address, and note the outdoor temperature and humidity at the time.", + "call_a_technician_when": "Checking the float switch, testing the drain pump circuit, and clearing a condensate line inside the indoor unit require the electrical enclosure to be opened, which is qualified service work. | Water staining on a ceiling, a wall, or an electrical accessory near the unit is a stop condition. Isolate the indoor unit and arrange service rather than running it to see whether the code returns.", + "reset_guidance": "A P5 stop clears when the level detection returns to normal, so a reset that appears to work has only emptied the tray. Treat a second occurrence as confirmation that the drain path needs measuring.", + "evidence_class": "oem-support", + "evidence_publishers": "Mitsubishi Electric; Mitsubishi Electric Trane HVAC US", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/mitsubishi/p5-drain-pump-protection/" + }, { "id": "brands/mitsubishi/p6-freeze-overheat-protection", "brand": "Mitsubishi Electric", @@ -1163,6 +2163,66 @@ "last_reviewed": "2026-09-03", "reference_url": "https://hvac-bench.com/brands/mitsubishi/p8-fault-code/" }, + { + "id": "brands/mitsubishi/u2-discharge-temperature-protection", + "brand": "Mitsubishi Electric", + "brand_slug": "mitsubishi", + "error_code": "U2", + "equipment_type": "heat-pump", + "product_family": "Mitsubishi Electric outdoor units publishing the U-series fault table, including M-Series and MXZ multi-zone outdoor equipment", + "models": "MUZ-GL series; MUZ-FH series; MXZ-C series; MXZ-SM series", + "fault_category": "protection-shutdown", + "title": "Mitsubishi U2: high discharge temperature is a charge question, not a compressor verdict", + "meaning": "U2 is an outdoor protection stop raised when the compressor discharge temperature rises beyond the limit the control allows, a condition the reference also ties to refrigerant shortage. High discharge temperature is what a compressor does when it has too little refrigerant returning to cool it, so the code is a symptom of the refrigerant circuit rather than proof the compressor is damaged.", + "scope_note": "This applies to Mitsubishi Electric outdoor units that publish the U-series table. The same two characters appear on other manufacturers with unrelated meanings, and Mitsubishi Heavy Industries is a separate company with its own code set. Take the reading from the outdoor unit model plate, not from the brand name on the indoor grille.", + "owner_safe_checks": "Turn the system off at the controller and leave it off, since repeated restarts run the compressor under the condition that triggered the limit. | Walk the visible line set and the outdoor unit looking for oil film, frost patches, or a disturbed insulation run, and photograph anything you find. | Write down how the system had been performing over the preceding weeks and the outdoor conditions when it stopped.", + "call_a_technician_when": "Measuring charge, searching for a leak, recovering refrigerant, and testing the discharge thermistor are certified refrigerant-handling activities under EPA Section 608 in the United States and F-Gas rules in the United Kingdom and Europe. | Do not add refrigerant, tighten a flare, or operate the system to see whether the code stays away. Running a compressor at high discharge temperature is what the protection exists to prevent.", + "reset_guidance": "Power cycling clears the stored stop, and the protection then re-evaluates the discharge temperature as soon as the compressor runs. A code that returns on the next cycle is reporting a live condition, so leave the system off.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Mitsubishi Electric", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/mitsubishi/u2-discharge-temperature-protection/" + }, + { + "id": "brands/mitsubishi/u6-compressor-overcurrent", + "brand": "Mitsubishi Electric", + "brand_slug": "mitsubishi", + "error_code": "U6", + "equipment_type": "heat-pump", + "product_family": "Mitsubishi Electric inverter outdoor units publishing the U-series fault table, including M-Series single-zone and MXZ multi-zone equipment", + "models": "MUZ-GL series; MUZ-FS series; MXZ-C series; MXZ-SM series", + "fault_category": "inverter-module-protection", + "title": "Mitsubishi U6: the inverter cut the compressor current before anything melted", + "meaning": "U6 is raised when the outdoor inverter detects compressor current or power module conditions outside the range it will drive. It is an electrical protection acting in milliseconds, which is why the code arrives as an abrupt stop rather than a gradual loss of output. The detection names the current, not the cause of the current.", + "scope_note": "The entry described here belongs to Mitsubishi Electric outdoor units publishing the U-series table. Multi-zone outdoor units serving several indoor heads report the code centrally, so the address shown does not identify a room. Confirm the outdoor model from its plate before applying this reading.", + "owner_safe_checks": "Attempt at most one restart from the controller, then stop and note how long the outdoor unit ran before the code returned. | Check whether other appliances on the property are behaving normally and whether any protective device in the consumer unit or panel has operated. | Leave the isolator on and the operation off for several hours before any further attempt if the system has been unused for a long period.", + "call_a_technician_when": "Measuring compressor winding resistance, drive output, and supply voltage under load requires opening an energised outdoor enclosure and is qualified work. | A burning smell, visible scorching, or a protective device that trips when the unit starts is a stop condition. Isolate at the dedicated switch and arrange service without further attempts.", + "reset_guidance": "One controlled restart is reasonable to establish whether the stop repeats. Beyond that, each attempt repeats the electrical event the protection was defending against, so leave the system off until it is measured.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Mitsubishi Electric", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/mitsubishi/u6-compressor-overcurrent/" + }, + { + "id": "brands/mitsubishi-heavy-industries/e-series-error-codes", + "brand": "Mitsubishi Heavy Industries", + "brand_slug": "mitsubishi-heavy-industries", + "error_code": "E-series", + "equipment_type": "ductless-mini-split", + "product_family": "Mitsubishi Heavy Industries room air conditioners documented in the MHI user manual library", + "models": "SRK ZS-W wall units; SRK ZSX-W wall units; SRF floor-standing units; SRR ducted indoor units", + "fault_category": "communication-fault", + "title": "Mitsubishi Heavy Industries E codes are not Mitsubishi Electric codes", + "meaning": "Mitsubishi Heavy Industries publishes its own E-series fault codes, and they are unrelated to the codes used by Mitsubishi Electric despite the shared name. The two are separate companies with separate engineering, so a code table found for one will mislead on the other, sometimes convincingly.", + "scope_note": "This page concerns Mitsubishi Heavy Industries room air conditioners documented in the MHI user manual library. Mitsubishi Electric equipment, sold as M-Series, Mr Slim, and Ecodan, is documented separately and carries different code meanings for the same characters.", + "owner_safe_checks": "Read the full manufacturer name and model number from the outdoor unit data plate and write them down before searching anything. | Note which indoor units are affected and which continue to work normally. | Confirm whether the remote control is still being acknowledged by the affected unit.", + "call_a_technician_when": "Testing the interconnecting cable, inspecting boards, and correcting address or configuration settings require the casings to be opened by a qualified technician. | Interconnecting cable between indoor and outdoor units carries mains voltage on this equipment, so it is not something to inspect, strip, or reterminate without the appropriate qualification.", + "reset_guidance": "Signalling is re-established from scratch whenever the equipment powers up, which is why one restart is a genuine test here. A code that comes back within seconds describes a path that is still broken.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Mitsubishi Heavy Industries Thermal Systems", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/mitsubishi-heavy-industries/e-series-error-codes/" + }, { "id": "brands/mrcool/el01-e1-error-code", "brand": "MRCOOL", @@ -1183,6 +2243,26 @@ "last_reviewed": "2026-09-02", "reference_url": "https://hvac-bench.com/brands/mrcool/el01-e1-error-code/" }, + { + "id": "brands/mrcool/diy-error-codes-by-generation", + "brand": "MRCOOL", + "brand_slug": "mrcool", + "error_code": "Generation-dependent codes", + "equipment_type": "ductless-mini-split", + "product_family": "MRCOOL DIY ductless systems across the third, fourth, and fifth generations documented in MRCOOL support", + "models": "DIY 3rd generation; DIY 4th generation; DIY 5th generation", + "fault_category": "communication-fault", + "title": "MRCOOL DIY codes changed between generations, and so did the format", + "meaning": "MRCOOL changed both the numbering and the format of its DIY codes between generations. A condition shown as P4 on earlier equipment appears as PC-04 on fourth generation units, and searching one format while owning the other returns answers that look right and are not.", + "scope_note": "MRCOOL DIY generations differ in refrigerant, cable, port count, and control firmware as well as in code format. The generation has to be established from the model and the documentation supplied with the equipment, and MRCOOL publishes the differences between fourth and fifth generation explicitly.", + "owner_safe_checks": "Photograph the displayed code exactly as it appears, including any hyphen or leading characters. | Find the documentation supplied with the equipment and confirm which DIY generation it covers. | Where more than one MRCOOL system is installed, record which unit each code came from.", + "call_a_technician_when": "Refrigerant work on any generation requires certification, and the newer refrigerant carries its own handling and room-size considerations. | Self-installed equipment does not change who may open a refrigerant circuit. The pre-charged line set is designed to be connected without opening the circuit, and anything beyond that is certified work.", + "reset_guidance": "MRCOOL support describes isolating power at the breaker for a stated interval before certain checks, and the interval belongs to the generation as much as the code does. Follow the document that matches your equipment.", + "evidence_class": "oem-support", + "evidence_publishers": "MRCOOL", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/mrcool/diy-error-codes-by-generation/" + }, { "id": "brands/mrcool/p0-pc00-error-code", "brand": "MRCOOL", @@ -1263,6 +2343,46 @@ "last_reviewed": "2026-09-03", "reference_url": "https://hvac-bench.com/brands/nibe/f2120-alarm-228/" }, + { + "id": "brands/nibe/alarm-log-and-history", + "brand": "NIBE", + "brand_slug": "nibe", + "error_code": "Alarm log", + "equipment_type": "heat-pump", + "product_family": "NIBE air source and ground source heat pumps with controllers that store an alarm log and operating history", + "models": "NIBE F2120; NIBE S2125; NIBE F1155; NIBE SMO and VVM controllers", + "fault_category": "protection-shutdown", + "title": "NIBE alarms: the log is worth more than the alarm on screen", + "meaning": "A NIBE controller stores more than the alarm currently displayed. It keeps a history of previous alarms with timestamps and, on many models, operating values recorded alongside them, and that history answers questions the current alarm cannot: whether this has happened before, how often, and under what conditions.", + "scope_note": "NIBE controllers differ between the F, S, SMO, and VVM families in what they log and how it is reached, and an alarm number is interpreted against the manual for that controller. A number from one family should not be applied to another even within the NIBE range.", + "owner_safe_checks": "Photograph the current alarm, then open the alarm log and photograph the history with its timestamps. | Capture any operating values the controller displays alongside the log, including flow and return temperatures. | Note the outdoor conditions and what the system was being asked for when the alarm occurred.", + "call_a_technician_when": "Refrigerant-side alarms require a certified handler under F-Gas rules in the United Kingdom and European Union and under EPA Section 608 in the United States. | Adjusting flow rates, pump settings, or controller parameters on a heat pump installation affects how the equipment operates across its whole envelope and belongs to the commissioning installer.", + "reset_guidance": "Clearing an alarm lets the system continue and does not remove the entry from the log, which is why the log is the reliable record. Capture it first in case a reset is performed before you are asked.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "NIBE", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/nibe/alarm-log-and-history/" + }, + { + "id": "brands/panasonic/f-series-refrigeration-cycle-codes", + "brand": "Panasonic", + "brand_slug": "panasonic", + "error_code": "F-series", + "equipment_type": "ductless-mini-split", + "product_family": "Panasonic room air conditioners with the self-diagnosis function described in Panasonic service documentation", + "models": "Panasonic Etherea; Panasonic TZ series; Panasonic Z series; Panasonic ducted indoor units", + "fault_category": "protection-shutdown", + "title": "Panasonic F-series codes: the self-diagnosis that points at the cycle", + "meaning": "Panasonic groups its self-diagnosis codes by leading character, and the F-series concerns the refrigeration cycle rather than communication or sensing alone. An F entry says the equipment evaluated how the cycle was behaving and found it outside what it expects, which is a statement about refrigerant, flow, and heat transfer together.", + "scope_note": "Panasonic self-diagnosis is present across room air conditioner ranges but the retrieval method and the code tables differ by generation. The codes described here belong to the residential air conditioning documentation; Aquarea air-to-water equipment uses a separate scheme entirely.", + "owner_safe_checks": "Find and follow the self-diagnosis retrieval sequence for your model rather than interpreting an indicator pattern by eye. | Clean the indoor filters and confirm the outdoor unit has clear space around it on all sides. | Note how performance changed over recent weeks and time the interval between stop and restart if the system is cycling.", + "call_a_technician_when": "Connecting gauges, measuring charge, and testing expansion device operation are certified refrigerant tasks and require the system to be running under supervision. | Do not add refrigerant in response to a cycle code. Charge is a measured quantity on this equipment, not something to be topped up until symptoms change.", + "reset_guidance": "Interrupting power clears a displayed code but may also clear stored self-diagnosis history on some models, so retrieve and photograph the code before any reset is attempted.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Panasonic", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/panasonic/f-series-refrigeration-cycle-codes/" + }, { "id": "brands/panasonic/f11-four-way-valve", "brand": "Panasonic", @@ -1383,6 +2503,26 @@ "last_reviewed": "2026-09-03", "reference_url": "https://hvac-bench.com/brands/pioneer/refrigerant-detector-codes/" }, + { + "id": "brands/pioneer/p-series-protection-codes", + "brand": "Pioneer", + "brand_slug": "pioneer", + "error_code": "P-series", + "equipment_type": "ductless-mini-split", + "product_family": "Pioneer Diamante and Quantum ductless systems whose code lists are published in Pioneer support", + "models": "Diamante series; Diamante Ultra; Quantum series", + "fault_category": "protection-shutdown", + "title": "Pioneer P codes: protections that stop the system on purpose", + "meaning": "A Pioneer code beginning with P marks a protection: the equipment measured something outside its permitted range and shut itself down before harm could follow. That is a description of a decision, not an accusation against a component, and the difference decides where a technician starts.", + "scope_note": "Pioneer publishes code lists per system family, and the Diamante and Quantum lists are the ones referenced here. Pioneer equipment from earlier generations, and equipment sold under other names on related hardware, carries its own list. Confirm the family from the indoor and outdoor model numbers first.", + "owner_safe_checks": "Photograph the display showing the full code, including every character after the letter. | Clean the indoor filters and clear the space around the outdoor unit, then note whether behaviour changes. | Log the run time before each shutdown and the outdoor temperature at the time.", + "call_a_technician_when": "Weighing the charge, hunting a leak, and washing a coil all fall inside the certification regimes: EPA Section 608 across the United States, and the F-Gas framework in Britain and the European Union. | Repeated restarts return the equipment to the condition the protection stopped, so they are not a substitute for a measurement.", + "reset_guidance": "A protection re-measures as soon as operation resumes, so a code returning quickly reports a live condition. One restart confirms that; repeating it adds heat and current cycles without adding information.", + "evidence_class": "oem-support", + "evidence_publishers": "Pioneer", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/pioneer/p-series-protection-codes/" + }, { "id": "brands/rheem/furnace-ignition-lockout-and-reset", "brand": "Rheem", @@ -1403,6 +2543,26 @@ "last_reviewed": "2026-09-08", "reference_url": "https://hvac-bench.com/brands/rheem/furnace-ignition-lockout-and-reset/" }, + { + "id": "brands/rheem/furnace-two-blinks-pressure-switch", + "brand": "Rheem", + "brand_slug": "rheem", + "error_code": "2 blinks", + "equipment_type": "furnace", + "product_family": "Rheem R96V modulating condensing gas furnaces documented in the Rheem service literature", + "models": "R96VA0601317; R96VA0851521; R96VA1152521", + "fault_category": "pressure-switch-fault", + "title": "Rheem two blinks: the draft proving circuit stopped the sequence", + "meaning": "Two blinks on a Rheem furnace control identifies a pressure switch condition in the draft proving circuit. The switch is the device that tells the control whether the inducer has established the airflow the burner needs, so the blink count locates the circuit that failed to reach its expected state rather than the part that caused it.", + "scope_note": "This reading follows the diagnostic table published for the Rheem R96V modulating condensing furnace. Rheem and Ruud have used different blink assignments across control generations, and a chart written for another Rheem furnace line can give a different meaning for the same count. Match the model on the rating plate.", + "owner_safe_checks": "Count the blinks carefully, since two blinks and three blinks are easy to confuse when the pause between groups is short. | View the vent and intake terminations from ground level and note ice, snow, nests, or vegetation without climbing or reaching in. | Record the outdoor temperature, wind, and whether ignition was ever attempted on each failed cycle.", + "call_a_technician_when": "Measuring draft pressure against the published value, inspecting the inducer wheel, and clearing condensate paths are licensed gas-furnace tasks. | A pressure switch must never be bridged or bypassed to make a furnace run, because it is the only device confirming that combustion products are leaving the building.", + "reset_guidance": "Interrupting power clears the indication and the control repeats the same proving test on the next call. Where the cause is seasonal, an apparent fix after a reset may only be the weather changing.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Rheem", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/rheem/furnace-two-blinks-pressure-switch/" + }, { "id": "brands/rheem/r96v-fault-57", "brand": "Rheem", @@ -1463,6 +2623,46 @@ "last_reviewed": "2026-09-03", "reference_url": "https://hvac-bench.com/brands/ruud/r96t-fault-58/" }, + { + "id": "brands/ruud/furnace-blink-code-reading", + "brand": "Ruud", + "brand_slug": "ruud", + "error_code": "Blink patterns", + "equipment_type": "furnace", + "product_family": "Ruud gas furnaces whose integrated controls report diagnostics through a blinking indicator, including the R96T range", + "models": "R96T series; R95T series; Ruud Achiever furnaces", + "fault_category": "communication-fault", + "title": "Ruud blink codes: counting correctly is most of the diagnosis", + "meaning": "A Ruud furnace control reports its diagnosis as a number of blinks separated by pauses, and the number is the whole message. Two blinks and three blinks describe different conditions, the pause between groups is easy to miss, and a miscount sends the whole diagnosis somewhere it does not belong.", + "scope_note": "Blink assignments belong to a control platform rather than to the Ruud name, and they have differed across furnace ranges and generations. The diagnostic label inside the furnace door, and the installation instructions for the model on the rating plate, are the reference for what a given count means.", + "owner_safe_checks": "Record a video through the door sight glass across several full repetitions rather than counting by eye. | Keep the blower door closed, since opening it can remove control power and clear the indication. | Write the count down immediately with the date and time, and note whether it has changed between attempts.", + "call_a_technician_when": "Interpreting a count against the diagnostic label, testing components, and any work inside the furnace cabinet are licensed gas-furnace tasks. | A count corresponding to a limit, a rollout, or a flame condition is a stop condition rather than something to observe across further cycles.", + "reset_guidance": "Cutting power clears the indication and the control repeats its checks on the next call for heat, so the pattern returns if the condition remains. Capture it before any reset, since the sight glass is the only place it appears.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Ruud", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/ruud/furnace-blink-code-reading/" + }, + { + "id": "brands/samsung/c1-service-error-codes", + "brand": "Samsung", + "brand_slug": "samsung", + "error_code": "C1 (21, 22, 54, 63)", + "equipment_type": "ductless-mini-split", + "product_family": "Samsung indoor air conditioner units that display the C1 group of service codes described in Samsung support material", + "models": "Wall-mounted indoor units; Cassette indoor units; Duct-type indoor units; Floor-standing indoor units", + "fault_category": "temperature-sensor-fault", + "title": "Samsung C1 codes: four faults Samsung sends straight to an engineer", + "meaning": "Samsung publishes four indoor faults under a C1 heading with a two-digit detail: a defective room temperature sensor, a defective heat exchanger temperature sensor, a fan that is not rotating, and EEPROM data corruption. For all four, Samsung's stated instruction is to contact a service centre, so none of them has an owner-level remedy.", + "scope_note": "These four entries are drawn from Samsung indoor air conditioner support material. Samsung display conventions differ between generations and regions, and the same four faults appear on other Samsung equipment as longer numeric codes. Confirm against the manual for your own indoor unit before matching a detail digit to a component.", + "owner_safe_checks": "Read and photograph the full display, including both parts of the code, before the unit is switched off or the power is interrupted. | Establish whether the indoor fan produces any airflow at any setting, standing clear of the outlet while you check. | Compare the displayed room temperature with a separate thermometer and note both figures with the date.", + "call_a_technician_when": "Samsung's stated instruction for every fault in this group is to contact a service centre, and each of the four sits behind the indoor casing. | Do not run the system with an indoor fan that is not turning. Air moving across the coil is what keeps the refrigerant circuit inside its designed operating range.", + "reset_guidance": "Samsung permits an interruption of a few minutes at the plug or the breaker as a general step, and states that a code returning afterwards means the product should not be used until service. Treat one attempt as the limit.", + "evidence_class": "oem-support", + "evidence_publishers": "Samsung Electronics; Samsung", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/samsung/c1-service-error-codes/" + }, { "id": "brands/samsung/windfree-c101-c102-error", "brand": "Samsung", @@ -1483,6 +2683,26 @@ "last_reviewed": "2026-09-03", "reference_url": "https://hvac-bench.com/brands/samsung/windfree-c101-c102-error/" }, + { + "id": "brands/samsung/cf-ci-df-display-codes", + "brand": "Samsung", + "brand_slug": "samsung", + "error_code": "CF / CI / dF", + "equipment_type": "ductless-mini-split", + "product_family": "Samsung indoor air conditioner units whose display shows the reminder and operating-mode characters described in Samsung support", + "models": "Wall-mounted indoor units; Cassette indoor units; Duct-type indoor units", + "fault_category": "filter-maintenance", + "title": "Samsung CF, CI, and dF: three displays that are not faults at all", + "meaning": "Samsung separates its indoor display characters into ones that need no service and ones that do. CF is a filter cleaning reminder, CI is the auto clean function running after the unit is switched off, and dF is the defrost operation during heating. Samsung states that the defrost display is not a product defect but one of the modes used to protect the outdoor unit.", + "scope_note": "These three displays come from Samsung support material for indoor air conditioner units. Samsung markets equipment across many regions and display conventions differ between generations, so an older or a commercial Samsung indoor unit may not use the same characters. Check the manual supplied with the indoor unit before assuming a display is benign.", + "owner_safe_checks": "Read the two characters carefully, since a letter and a digit can look alike on a small indoor display at a distance. | Clean or replace the indoor filters following the manual for your unit, then clear the reminder using the remote control. | Time a defrost pause from when heating stops to when it returns, so an unusually long pause can be reported accurately.", + "call_a_technician_when": "A display that Samsung places in its service group, rather than these three, needs an authorised engineer and is not an owner task. | Frost that keeps returning after every defrost cycle, or a defrost pause that never ends, is a fault behind a normal-looking display and should be reported.", + "reset_guidance": "Only the filter reminder is designed to be cleared by the user, and the remote control does it. The auto clean and defrost displays end on their own when the function completes.", + "evidence_class": "oem-support", + "evidence_publishers": "Samsung Electronics; Samsung", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/samsung/cf-ci-df-display-codes/" + }, { "id": "brands/senville/ec51-error-code", "brand": "Senville", @@ -1543,6 +2763,46 @@ "last_reviewed": "2026-09-02", "reference_url": "https://hvac-bench.com/brands/senville/pc0a-error-code/" }, + { + "id": "brands/senville/codes-differ-between-series", + "brand": "Senville", + "brand_slug": "senville", + "error_code": "Series-dependent codes", + "equipment_type": "ductless-mini-split", + "product_family": "Senville ductless mini-split systems across the Aura, Leto, and earlier series documented in Senville support", + "models": "Aura series; Leto series; SENA and SENL model prefixes", + "fault_category": "communication-fault", + "title": "Senville codes: the same characters mean different things by series", + "meaning": "Senville publishes different code tables for its Aura, Leto, and earlier series, and the same two characters can describe unrelated conditions between them. The series therefore has to be established before the code is looked up, and the model prefix on the data plate is what establishes it.", + "scope_note": "Senville systems are identified by model prefix rather than by the name printed on the front panel, and the same series name has covered more than one generation. The support document that matches your exact model number is the reference, and a chart labelled only with the brand is not.", + "owner_safe_checks": "Photograph the data plates on the indoor and outdoor units and read the full model numbers from the images. | Photograph the displayed code before interrupting power for any reason. | Note whether the system fails at startup or after a period of running, since that alone separates two groups of conditions.", + "call_a_technician_when": "Testing the interconnecting cable, sensing elements, and boards requires casings that carry mains voltage to be opened, which is qualified work. | Conditions reached after a period of operation involve the refrigerant circuit on this equipment, and that is certified activity rather than an owner check.", + "reset_guidance": "Interrupting power clears a displayed code and lets the system re-evaluate, so one restart distinguishes a latched report from a live condition. Capture the code and the model numbers before doing it.", + "evidence_class": "oem-support", + "evidence_publishers": "Senville", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/senville/codes-differ-between-series/" + }, + { + "id": "brands/stiebel-eltron/wpl-fault-handling", + "brand": "Stiebel Eltron", + "brand_slug": "stiebel-eltron", + "error_code": "Fault and parameter conditions", + "equipment_type": "heat-pump", + "product_family": "Stiebel Eltron WPL air source heat pumps commissioned through the manufacturer parameter set", + "models": "WPL A; WPL AC; WPL classic range", + "fault_category": "protection-shutdown", + "title": "Stiebel Eltron WPL faults: commissioning parameters that look like breakdowns", + "meaning": "A Stiebel Eltron WPL is commissioned rather than simply installed, and a large share of what owners report as faults are parameters doing exactly what they were set to do. Heating curves, bivalent points, and blocking times all change behaviour beyond recognition without anything being wrong with the machine.", + "scope_note": "WPL spans several generations with different controllers and different parameter names, and commissioning values are chosen for the building rather than supplied as defaults. The commissioning record for your installation matters as much as the manual, and an installer holds both.", + "owner_safe_checks": "Keep a simple record of when the system stops and starts over several days, noting the time rather than only the symptom. | Note the outdoor temperature and the indoor temperature achieved during the coldest weather you experience. | Ask whoever installed the system for the commissioning record, including the heating curve and the bivalent point.", + "call_a_technician_when": "Altering a heating curve or a bivalent point changes how a heat pump operates across its whole envelope, so the installer who commissioned it is the right person to adjust it. | Anything on the sealed refrigerant side of a WPL requires a certified handler under the F-Gas framework, and that boundary is unaffected by what the controller shows.", + "reset_guidance": "Where the behaviour comes from a parameter, there is nothing to reset: the system is doing what it was configured to do and will do it again tomorrow. Establish whether a fault exists before treating it as one.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Stiebel Eltron", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/stiebel-eltron/wpl-fault-handling/" + }, { "id": "brands/tado/smart-radiator-thermostat-e1", "brand": "tado", @@ -1583,6 +2843,46 @@ "last_reviewed": "2026-09-03", "reference_url": "https://hvac-bench.com/brands/tado/radiator-thermostat-e2-e4/" }, + { + "id": "brands/tado/heat-demand-not-reaching-boiler", + "brand": "tado", + "brand_slug": "tado", + "error_code": "Heat demand not delivered", + "equipment_type": "controls-thermostats", + "product_family": "tado smart thermostat systems using a wireless receiver or an extension kit between the control and the heating appliance", + "models": "tado Smart Thermostat; tado Wireless Receiver; tado Extension Kit; tado X", + "fault_category": "communication-fault", + "title": "tado calling for heat with nothing happening: where the demand stops", + "meaning": "When a tado control shows a heat demand and the appliance stays cold, the demand is stopping somewhere between the two. The chain runs from the thermostat, through the radio link, to a receiver or extension kit, and finally through a pair of contacts into the boiler, and each of those can fail while the one before it reports success.", + "scope_note": "tado has shipped several generations with different radio arrangements, including the newer tado X range which is not wired or paired like its predecessors. Match the product names on the devices you actually own to the tado support material for that generation before following any instruction.", + "owner_safe_checks": "Try to produce heat from the appliance or from any control other than tado, and note whether it works. | Look at the receiver or extension kit and note whether it shows any indication at all. | Write down anything that changed in the property recently, including furniture, appliances, routers, or a relocated thermostat.", + "call_a_technician_when": "Wiring between a receiver and a heating appliance carries mains voltage on United Kingdom installations, so terminal work belongs to a qualified person. | An appliance that produces no heat by any route is a heating fault and needs a Gas Safe registered engineer rather than control support.", + "reset_guidance": "Restarting the app or the thermostat restores a software link and cannot close a contact that has no supply. Establish whether the appliance heats by another route before restarting anything.", + "evidence_class": "oem-support", + "evidence_publishers": "tado", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/tado/heat-demand-not-reaching-boiler/" + }, + { + "id": "brands/tcl/filter-and-service-indicators", + "brand": "TCL", + "brand_slug": "tcl", + "error_code": "Indicator group", + "equipment_type": "ductless-mini-split", + "product_family": "TCL residential split air conditioners documented in the TCL product download library", + "models": "TCL Elite series; TCL Breeze series; TCL Flexi series", + "fault_category": "filter-maintenance", + "title": "TCL indicators: telling a maintenance reminder from a real fault", + "meaning": "TCL indoor units use the same indicator panel for maintenance reminders and for faults, which means the first question is always which kind of indication you are looking at. A filter reminder is cleared by the owner after cleaning; a fault indication is not, and trying to clear one as though it were the other wastes time.", + "scope_note": "TCL publishes manuals per model in its download library rather than a single brand-wide code list, and indicator behaviour differs between ranges and generations. The manual for the model on your indoor unit is the reference for what each indication means and how it is cleared.", + "owner_safe_checks": "Establish first whether the unit still produces cooling or heating when asked, since that answers which kind of indication you are seeing. | Clean or replace the indoor filters following the manual, dry them fully before refitting, and then carry out the model-specific reset. | Photograph the indicator panel before any reset if operation has stopped, so the indication is preserved.", + "call_a_technician_when": "An indication accompanied by the unit refusing to operate is a fault report and needs a qualified technician rather than owner maintenance. | Do not open the indoor casing beyond the filter access the manual describes. Anything further sits alongside the board and the fan supply.", + "reset_guidance": "A maintenance reminder has a documented reset sequence and is designed to be cleared by the owner. A fault indication has no such sequence, and interrupting power only removes the display.", + "evidence_class": "oem-support", + "evidence_publishers": "TCL", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/tcl/filter-and-service-indicators/" + }, { "id": "brands/toshiba/e01-e02-e03-controller-communication", "brand": "Toshiba", @@ -1603,6 +2903,26 @@ "last_reviewed": "2026-09-09", "reference_url": "https://hvac-bench.com/brands/toshiba/e01-e02-e03-controller-communication/" }, + { + "id": "brands/toshiba/p-series-protection-codes", + "brand": "Toshiba", + "brand_slug": "toshiba", + "error_code": "P-series", + "equipment_type": "ductless-mini-split", + "product_family": "Toshiba air conditioning equipment using the fault code tables published in the Toshiba United Kingdom technical handbook", + "models": "Toshiba Seiya; Toshiba Shorai Edge; Toshiba Haori; Toshiba Digital Inverter ducted", + "fault_category": "protection-shutdown", + "title": "Toshiba P-series protections: what the handbook groups under one letter", + "meaning": "Toshiba organises its fault codes by leading letter, and the P-series marks protective shutdowns rather than component failures. A P code means the equipment measured a condition outside its permitted range and stopped itself, which is a materially different statement from an E code reporting a communication or controller problem.", + "scope_note": "Toshiba's technical handbook covers a wide range of equipment sold in the United Kingdom, and the same code can appear against different subsystems on residential and on larger commercial equipment. Take the model from the outdoor and indoor data plates and read the code against the handbook table for that family.", + "owner_safe_checks": "Photograph the controller showing the complete code, including the letter and every digit that follows it. | Copy the indoor and outdoor model numbers from their data plates so the correct handbook table can be used. | Deal with the two airflow variables you can reach: wash the indoor filters and open up the space around the outdoor casing.", + "call_a_technician_when": "Refrigerant measurement, leak detection, and coil cleaning are certified activities under EPA Section 608 in the United States and F-Gas rules in the United Kingdom and European Union. | Repeatedly restarting a system that keeps reaching a protection puts the equipment back into the condition the protection stopped, which is worth avoiding.", + "reset_guidance": "A protection re-evaluates its measurement as soon as the system runs again, so a code returning quickly means the condition is live. One restart establishes that; more than one adds nothing.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Toshiba Air Conditioning", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/toshiba/p-series-protection-codes/" + }, { "id": "brands/trane/xv20i-184-07-and-184-08-cold-weather-lockout", "brand": "Trane", @@ -1623,6 +2943,46 @@ "last_reviewed": "2026-09-04", "reference_url": "https://hvac-bench.com/brands/trane/xv20i-184-07-and-184-08-cold-weather-lockout/" }, + { + "id": "brands/trane/furnace-flame-sense-after-ignition", + "brand": "Trane", + "brand_slug": "trane", + "error_code": "Flame sense fault", + "equipment_type": "furnace", + "product_family": "Trane gas furnaces whose integrated control proves flame by rectification, as described in Trane homeowner support for a burner that shuts off after ignition", + "models": "Trane S-series gas furnaces; Trane XC and XV series gas furnaces", + "fault_category": "flame-sense-fault", + "title": "Trane furnace burner lights then shuts off: reading the flame sense fault", + "meaning": "When a Trane furnace lights its burner and shuts down a few seconds later, the control has decided it cannot confirm the flame it just created. Trane treats that as a flame sensing condition. The burner did light, so the ignition side worked, and what failed was the proof step that keeps the gas valve open.", + "scope_note": "Trane support describes this behaviour for gas furnaces whose control proves flame by passing a small current through it. Trane also sells equipment where the same symptom has a different cause, and any numeric or flash code shown on your control is read from that model's own literature rather than from this description.", + "owner_safe_checks": "Listen to a complete heating call and note whether the burner lights at all, and how many seconds it stays alight. | Count how many calls succeed and how many fail over two or three days, including the time of day for each. | Replace a loaded filter with the specified clean one, since restricted airflow produces a different fault that can be confused with this one.", + "call_a_technician_when": "Measuring the flame signal in microamps, cleaning or repositioning a sensing electrode, and testing the ground path are licensed gas-furnace tasks. | Do not attempt to clean a sensing rod yourself. It sits in the burner compartment beside live components and a gas train, and an abrasive left on the surface makes the fault worse.", + "reset_guidance": "There is no reset that restores a weak flame signal. Cycling the thermostat simply spends more ignition attempts against the same measurement.", + "evidence_class": "oem-support", + "evidence_publishers": "Trane", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/trane/furnace-flame-sense-after-ignition/" + }, + { + "id": "brands/trane/air-handler-overflow-switch-shutdown", + "brand": "Trane", + "brand_slug": "trane", + "error_code": "Overflow switch trip", + "equipment_type": "air-handler", + "product_family": "Trane air handlers and indoor coils fitted with a condensate overflow switch, as described in Trane homeowner support", + "models": "Trane air handlers with factory or field-fitted overflow switches; Trane indoor coil assemblies with secondary drain pans", + "fault_category": "water-leak", + "title": "Trane overflow switch shutdown: cooling stops and nothing looks broken", + "meaning": "An overflow switch on a Trane air handler interrupts the cooling call when condensate rises past the level it watches. The outdoor unit stops, the thermostat still shows a call, and nothing inside the house looks wrong. That combination is the switch doing its job: it stops the system before water reaches the ceiling below.", + "scope_note": "Overflow switches are fitted in several positions, including the primary pan, the secondary pan, and in the drain line itself, and not every Trane installation has one. Which switch tripped and how it is wired depends on the installation rather than on the model, so the answer comes from the installer's arrangement as much as from Trane literature.", + "owner_safe_checks": "Confirm the thermostat is calling for cooling and that no breaker or fuse serving the indoor or outdoor unit has operated. | Look into any visible drain pan beneath the indoor unit and note whether it holds water or shows a waterline stain. | After the system has been asked to cool for a while, go and look at where the drain discharges outside and see whether anything came out.", + "call_a_technician_when": "Clearing a condensate drain line, testing an overflow switch, and correcting drain fall or trap arrangement are service tasks on this equipment. | Never bypass or unplug an overflow switch to restore cooling. It is the only thing standing between a blocked drain and water in the structure below.", + "reset_guidance": "The switch closes again on its own once the level falls, so cooling can appear to return without anything being fixed. Treat a self-restoring shutdown as the same fault, not as a resolved one.", + "evidence_class": "oem-support", + "evidence_publishers": "Trane", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/trane/air-handler-overflow-switch-shutdown/" + }, { "id": "brands/vaillant/ecotec-f22-low-pressure", "brand": "Vaillant", @@ -1643,6 +3003,26 @@ "last_reviewed": "2026-09-09", "reference_url": "https://hvac-bench.com/brands/vaillant/ecotec-f22-low-pressure/" }, + { + "id": "brands/vaillant/ecotec-f23-water-circulation", + "brand": "Vaillant", + "brand_slug": "vaillant", + "error_code": "F.23", + "equipment_type": "boiler", + "product_family": "Vaillant ecoTEC gas boilers covered by the Vaillant United Kingdom fault code list", + "models": "ecoTEC plus combi; ecoTEC plus system; ecoTEC exclusive", + "fault_category": "water-circulation-fault", + "title": "Vaillant F.23: the temperature spread says water is barely moving", + "meaning": "Vaillant defines F.23 as the temperature spread being too great, or water circulation too low. The boiler measures flow and return temperature and compares them, and when the difference grows beyond what the appliance allows, it concludes that not enough water is passing through the heat exchanger to carry the heat away.", + "scope_note": "The definition used here is Vaillant's own fault code list for ecoTEC appliances sold in the United Kingdom. Vaillant uses different fault numbering on other ranges and in other markets, and a Glow-worm appliance, though part of the same group, has its own published list. Check the code against the label inside your own casing flap.", + "owner_safe_checks": "Feel each radiator after a heating attempt and note which get warm, which stay cold, and whether the cold ones are cold at the top or the bottom. | Check the pressure gauge and record the reading, since a system that has lost water often has air in its place. | Confirm that radiator valves and any thermostatic heads have not been closed off, particularly on circuits recently worked on.", + "call_a_technician_when": "Setting or replacing a pump, venting a sealed primary circuit, power flushing, and testing flow and return sensors are Gas Safe registered tasks on this appliance. | Kettling or banging from the boiler is a reason to stop using the heating rather than to keep trying, because boiling against the exchanger causes cumulative damage.", + "reset_guidance": "Resetting allows another firing attempt against unchanged circulation, and each attempt puts the exchanger through the same conditions. Two attempts establish that the fault repeats; more than that is not diagnosis.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Vaillant UK; Vaillant", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/vaillant/ecotec-f23-water-circulation/" + }, { "id": "brands/vaillant/ecotec-f28-and-f29", "brand": "Vaillant", @@ -1663,6 +3043,26 @@ "last_reviewed": "2026-09-08", "reference_url": "https://hvac-bench.com/brands/vaillant/ecotec-f28-and-f29/" }, + { + "id": "brands/vaillant/ecotec-f32-fan-fault", + "brand": "Vaillant", + "brand_slug": "vaillant", + "error_code": "F.32", + "equipment_type": "boiler", + "product_family": "Vaillant ecoTEC gas boilers covered by the Vaillant United Kingdom fault code list", + "models": "ecoTEC plus combi; ecoTEC plus system; ecoTEC pro", + "fault_category": "fan-fault", + "title": "Vaillant F.32: no fan means no combustion, by design", + "meaning": "Vaillant gives F.32 as the fan being faulty or not connected. On a room-sealed condensing boiler the fan is what draws combustion air in and pushes flue gases out, so the appliance cannot burn gas safely without it. The lockout is not the boiler being cautious; it is the only acceptable response to losing forced draught.", + "scope_note": "This definition comes from Vaillant's fault code list for ecoTEC appliances in the United Kingdom. The same number means something else on other manufacturers and on some Vaillant ranges outside the ecoTEC family, so read it against the list printed inside the casing flap of your own boiler.", + "owner_safe_checks": "Listen at the start of an attempt and note whether any fan sound occurs at all, and whether it sounds as it used to. | Record the exact code and how many attempts produce the same result before you stop trying. | Check whether any recent service, part replacement, or electrical work preceded the fault.", + "call_a_technician_when": "Testing, cleaning, or replacing a boiler fan and its wiring is Gas Safe registered work on a sealed combustion appliance in the United Kingdom. | Resist the urge to take the front panel off for a look. On a room-sealed appliance that panel is a safety component, and opening it breaks the separation it exists to maintain.", + "reset_guidance": "Resetting permits another attempt, and the appliance re-tests the fan within seconds. Where the fan genuinely cannot run, no number of resets changes that, and the lockout is doing its job by refusing.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Vaillant UK; Vaillant", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/vaillant/ecotec-f32-fan-fault/" + }, { "id": "brands/vaillant/ecotec-plus-f75-fault", "brand": "Vaillant", @@ -1703,6 +3103,26 @@ "last_reviewed": "2026-09-03", "reference_url": "https://hvac-bench.com/brands/viessmann/vitodens-100w-fault-59/" }, + { + "id": "brands/viessmann/vitodens-burner-lockout-codes", + "brand": "Viessmann", + "brand_slug": "viessmann", + "error_code": "Burner lockout group", + "equipment_type": "boiler", + "product_family": "Viessmann Vitodens gas condensing boilers whose displayed fault codes are listed in the Viessmann fault checker", + "models": "Vitodens 050-W; Vitodens 100-W; Vitodens 111-W; Vitodens 200-W", + "fault_category": "ignition-lockout", + "title": "Viessmann burner lockouts: what the fault checker can and cannot settle", + "meaning": "A Viessmann burner lockout means the appliance attempted to establish combustion, failed to prove it within the permitted attempts, and stopped offering heat. Viessmann's own fault checker maps the displayed code to a condition, and the value of that tool is that it distinguishes lockouts from blocking faults, which behave and clear along different lines.", + "scope_note": "The Vitodens range spans wall-hung combi, system, and floor-standing appliances across several generations, and code meanings are model-specific. Enter the code into Viessmann's own checker together with the appliance model rather than relying on a list that does not ask which boiler you have.", + "owner_safe_checks": "Photograph the display showing the code, then copy the full model name and serial number from the appliance data plate. | Record whether the boiler recovered on its own or needed a reset, and how many times each has happened. | Check the system pressure gauge while the system is cold and note the reading.", + "call_a_technician_when": "Gas pressure measurement, ignition and sensing component work, flue inspection, and condensate system correction are Gas Safe registered tasks. | A boiler that locks out again immediately after a reset should be left alone rather than reset repeatedly, because each attempt spends further ignition cycles against the same condition.", + "reset_guidance": "One reset establishes whether a lockout returns immediately. Where the same code comes straight back, the appliance is reporting a live condition and further resets change nothing.", + "evidence_class": "oem-support", + "evidence_publishers": "Viessmann", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/viessmann/vitodens-burner-lockout-codes/" + }, { "id": "brands/worcester-bosch/greenstar-e9-219-overheat", "brand": "Worcester Bosch", @@ -1743,6 +3163,46 @@ "last_reviewed": "2026-09-03", "reference_url": "https://hvac-bench.com/brands/worcester-bosch/greenstar-si-ea-227-fault/" }, + { + "id": "brands/worcester-bosch/greenstar-fan-fault-codes", + "brand": "Worcester Bosch", + "brand_slug": "worcester-bosch", + "error_code": "Fan fault group", + "equipment_type": "boiler", + "product_family": "Worcester Bosch Greenstar gas boilers using the two-part display and fault code convention described in Worcester service instructions", + "models": "Greenstar i combi; Greenstar CDi Classic; Greenstar Si Compact; Greenstar 8000", + "fault_category": "fan-fault", + "title": "Worcester Greenstar fan faults: reading a code that has two halves", + "meaning": "Worcester Greenstar boilers report faults as a display code and a fault code together, and the pair is what identifies the condition. Fan-related entries in that convention describe the appliance being unable to establish or confirm the fan speed it requires, which prevents combustion because gas is metered against the air the fan delivers.", + "scope_note": "Worcester uses the two-part convention across the Greenstar range but the specific pairing differs between models and generations. Record both parts exactly as the display shows them and match them against the service instructions for the model on your appliance data plate rather than a list compiled elsewhere.", + "owner_safe_checks": "Photograph the display so that both code elements are captured, along with anything else shown on screen. | Copy the full model name and serial number from the data plate, which is behind or beneath the casing flap on most Greenstar appliances. | Listen during one start attempt and note whether a fan is audible and for how long.", + "call_a_technician_when": "Diagnosing and replacing a boiler fan, and testing its wiring and feedback, are Gas Safe registered tasks on a room-sealed appliance. | The casing forms part of the sealed enclosure between combustion and the room, so it is not removed for inspection by an occupant.", + "reset_guidance": "Worcester appliances allow a reset from the control panel, and one attempt shows whether the condition repeats. Reset before photographing the display and the pairing is lost.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "Worcester Bosch", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/worcester-bosch/greenstar-fan-fault-codes/" + }, + { + "id": "brands/york/yp9c-two-red-flashes", + "brand": "York", + "brand_slug": "york", + "error_code": "2 red flashes", + "equipment_type": "furnace", + "product_family": "York YP9C modulating condensing gas furnaces documented in the York installation manual", + "models": "YP9C060; YP9C080; YP9C100; YP9C120", + "fault_category": "pressure-switch-fault", + "title": "York YP9C two red flashes: the draft proving circuit did not behave", + "meaning": "Two red flashes on a York YP9C control points at the draft proving circuit: the pressure switch has not reached the state the control expects for the stage of the sequence it is in. The count identifies the circuit, not the component, so the inducer, the vent path, the condensate arrangement, and the switch itself are all inside the reading.", + "scope_note": "This applies to the York YP9C modulating condensing furnace as documented in its installation manual. York uses different flash tables on other furnace lines, and a modulating furnace proves draft across more than one firing rate, which changes what a fault at a particular stage implies compared with a single-stage appliance.", + "owner_safe_checks": "Count the flashes carefully through the sight glass, keeping the blower door closed so control power is not interrupted. | Check the outdoor vent and intake terminations from ground level for snow, ice, nests, or plant growth without climbing or probing. | Note whether ignition is ever attempted and whether the fault is linked to a change in firing rate.", + "call_a_technician_when": "Measuring draft pressure, testing the inducer, clearing condensate traps, and verifying switch operation at each firing rate are licensed gas-furnace tasks. | Any indoor smell of combustion products, or a carbon monoxide alarm, means leaving the appliance off, getting fresh air into the space, and calling the gas emergency number before anything else.", + "reset_guidance": "Removing power clears the display and the control repeats the same proving checks on the next call. A fault that tracks the weather can appear to be cleared by a reset when the conditions have simply changed.", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "York", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/york/yp9c-two-red-flashes/" + }, { "id": "brands/york/yp9c-three-red-flashes-at-low-fire", "brand": "York", @@ -1783,6 +3243,26 @@ "last_reviewed": "2026-09-09", "reference_url": "https://hvac-bench.com/brands/york/yp9c-four-red-flashes/" }, + { + "id": "brands/york/yp9c-five-red-flashes", + "brand": "York", + "brand_slug": "york", + "error_code": "5 red flashes", + "equipment_type": "furnace", + "product_family": "York YP9C modulating condensing gas furnaces documented in the York installation manual", + "models": "YP9C060; YP9C080; YP9C100; YP9C120", + "fault_category": "flame-out-of-sequence", + "title": "York YP9C five red flashes: flame where the control did not ask for it", + "meaning": "Five red flashes on a York YP9C control reports flame present at a time the control did not command it. That is a statement about the gas train rather than about ignition performance, so the furnace should be taken out of use and handed to a licensed engineer rather than reset and observed.", + "scope_note": "The flash table referenced here is the one published for the York YP9C modulating condensing furnace. York assigns flash counts differently across its furnace lines, and equipment from related brands on similar control platforms carries its own table, so the model on the rating plate governs.", + "owner_safe_checks": "Check for any smell of gas first, and if one is present leave the property and call the gas emergency number from outside before anything else. | Isolate the appliance using the service switch fitted beside it, which ends the cycling without touching anything inside the cabinet. | Write down whether continued warmth or burner activity was observed, and at what point in the cycle the flashes appear.", + "call_a_technician_when": "Gas valve testing, burner inspection, and flame sensing circuit measurement on a modulating condensing furnace are licensed gas engineering tasks. | Do not restore the furnace to service to see whether the code returns. A repeat cycle is the risk this code is warning about.", + "reset_guidance": "", + "evidence_class": "mixed-primary-sources", + "evidence_publishers": "York", + "last_reviewed": "2026-09-15", + "reference_url": "https://hvac-bench.com/brands/york/yp9c-five-red-flashes/" + }, { "id": "brands/york/yp9c-seven-red-flashes", "brand": "York",