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Air Conditioner / Heat Pump Error Codes: All Brands

Air conditioner and heat pump codes, shown on the indoor unit or the remote, often concern communication between indoor and outdoor units, temperature sensors, fan motors, high or low refrigerant pressure or a condensate drain problem. Safe first checks are cleaning the air filters, clearing leaves and debris from around the outdoor unit and checking the breaker. Work on the refrigerant circuit requires an EPA Section 608 certified technician.

34Codes
3.1Average severity
24%High or critical
59%DIY-friendly
Severity distributionSeverity distribution

ENERGY STAR certified models

Frigidaire · Air Conditioner / Heat Pump27
GE Appliances · Air Conditioner / Heat Pump14
LG · Air Conditioner / Heat Pump12
Whirlpool · Air Conditioner / Heat Pump6

Source: ENERGY STAR open data (data.energystar.gov) – number of certified models currently listed.

Official safety recalls (US CPSC)

Source: US Consumer Product Safety Commission recalls API. Check your model and serial number on the linked recall notice.

Most viewed

All codes (34)

11 Fujitsu · Air Conditioner / Heat Pump Error 11: the serial data link on terminal 3 between the Fujitsu indoor and outdoor units has… Moderate 126 Trane · Air Conditioner / Heat Pump 126 on a Trane ComfortLink II thermostat: it lost its data link to the furnace, air handler… Moderate 13 Carrier · Air Conditioner / Heat Pump A limit or rollout switch stayed open too long, so the furnace has locked itself out for 3… High 1dL Goodman · Air Conditioner / Heat Pump IdL (often read as 1dL) is not a fault: the furnace is powered and waiting for a call from… Minor 31 Carrier · Air Conditioner / Heat Pump The inducer couldn't prove a clear vent, so the pressure switch stayed open and the burners… Moderate 33 Carrier · Air Conditioner / Heat Pump A high-temperature safety switch opened, usually because too little air is moving through… Moderate 434 Lennox · Air Conditioner / Heat Pump The Lennox outdoor control can't talk to the inverter drive that runs the variable-speed… Moderate 51 Fujitsu · Air Conditioner / Heat Pump Error 51: the indoor fan ran far slower than commanded for about a minute, so the Fujitsu unit… Moderate A1 Daikin · Air Conditioner / Heat Pump The indoor unit's circuit board couldn't load or apply its settings, so the head refuses to run. Moderate A3 Daikin · Air Conditioner / Heat Pump A3 means condensate is backing up in the indoor unit's drain pan and the float switch has… Moderate CH05 LG · Air Conditioner / Heat Pump CH05: the LG indoor unit hears nothing back from the outdoor unit, so the compressor… Moderate CH10 LG · Air Conditioner / Heat Pump CH10: the indoor unit's fan motor isn't turning or isn't reporting its speed, so the unit shuts… Moderate CH21 LG · Air Conditioner / Heat Pump CH21: the outdoor inverter's power module saw a dangerous current peak and cut power… High CH38 LG · Air Conditioner / Heat Pump LG's protection stopped the system because the refrigerant level or pressure looks too low. High E1 Goodman · Air Conditioner / Heat Pump E1: the low-stage pressure switch reads closed before the inducer starts, so the furnace won't… Moderate E1 Gree · Air Conditioner / Heat Pump E1: refrigerant pressure on the high side got too high and the Gree unit stopped the compressor… Moderate E101 Samsung · Air Conditioner / Heat Pump The indoor unit waited too long for the outdoor unit to answer on the F1/F2 link and shut… Moderate E201 Samsung · Air Conditioner / Heat Pump E201: after power-up the outdoor unit couldn't find and register its indoor unit(s), so it… Moderate E5 Gree · Air Conditioner / Heat Pump E5: the Gree unit drew more current than allowed – often because supply voltage sagged… Moderate E6 Mitsubishi Electric · Air Conditioner / Heat Pump The indoor unit isn't getting valid signals back from the outdoor unit over the S3 wire. Moderate E6 Gree · Air Conditioner / Heat Pump E6 means the Gree indoor and outdoor units have lost their data link, so cooling and heating… Moderate E7 Daikin · Air Conditioner / Heat Pump The outdoor fan failed to spin up, or its speed signal went wrong, so the outdoor unit shut… Moderate EC Midea · Air Conditioner / Heat Pump EC: in cooling, the indoor coil didn't get colder after the compressor started – the unit… High EL01 MRCOOL · Air Conditioner / Heat Pump The MRCOOL indoor and outdoor units have stopped exchanging data, so the compressor won't run. Moderate H11 Panasonic · Air Conditioner / Heat Pump H11: the Panasonic indoor unit stopped getting valid signals from the outdoor unit after it… Moderate L5 Daikin · Air Conditioner / Heat Pump L5: the outdoor inverter saw a current spike on the compressor output and shut the compressor… High P1 MRCOOL · Air Conditioner / Heat Pump The outdoor unit saw supply voltage too high or too low and stopped the compressor to protect… Moderate P1 Mitsubishi Electric · Air Conditioner / Heat Pump P1: the indoor unit's return-air thermistor reads open or shorted, so the unit can't tell room… Low P4 Midea · Air Conditioner / Heat Pump P4 (PC 04 on newer displays): the outdoor board couldn't drive the inverter compressor… High P6 Mitsubishi Electric · Air Conditioner / Heat Pump P6: the indoor coil got too cold in cooling or too hot in heating – almost always an airflow… Low

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