Making sense of AC error codes

Air Conditioning FAQs

What are they?

An error code or flashing light popping up on any electrical equipment or their attendant remote can be a bit of a worry. These warnings speak for the system; telling users that a problem exists with either the inside or the outside unit. Generally when an error occurs the unit will shut itself off to prevent further damage.

Each error code has a meaning, which will allow users to understand what the problem is and thereby what needs to be done to fix it.

Do all brands have the same codes?

Error codes are particular to their manufacturers and their different models. There are many hundreds of codes used within the air conditioning industry. This means we cannot list them all here. However, we have list the main codes and brands in a table below.

What should I do when an error code pops up?

There are two main things you can do when you see the error code

  1. Reset the system to check that the error message itself is not an error

Try this only if you are confident in electrical equipment around the home. This process will delete the air conditioner’s on board memory, giving it a restart. Certain faults can be caused by the weather, lightning strikes, blackouts and brownouts or power fluctuations. These may be the reason for your air conditioner shutting down for safety reasons. While not always successful, it’s worth a try rather than spending money on a service call.

How: Separate your air conditioning system from its power supply. Unplugging it from a power point, turn off the isolator next to the outdoor unit or shut down your house’s power from the electrical board.

Leave for 15 – 30 minutes. During this time the on board memory will be deleted. Turn the power back on and restart your system. If the fault requires expert attention, then the error code will reappear.

  1. Call a technician.

If troubleshooting does not work we recommend getting a professional installer in to have a look. It’s safer plus you don’t want to cause any further damage to your unit, leaving you with a hefty repair bill. Compare can not only recommend someone to assist you, including companies who offer 24-7 repairs, but our friendly team can also conveniently lock in an appointment that suits you with one of our recommended companies. Hopefully, once someone can take a look, you’ll have some idea of what’s going on and the experts can ensure your system will be up and running smoothly in no time. It might also be a good time to book a full service to check everything is running as it should.

Error Code Table

You can find the more popular brands of air conditioner in the table below and match the code on the table to check out what it means. Both the codes and air conditioning brands have been listed in alphabetical order for your convenience. Even if you don’t reset your system it’s handy to have the code ready so the technician will know where the problem is.

NOTE: This is a general “quick reference” fault code list:

Daikin

Error Code and meaning
AO Indoor Error of external protection device

A1 Indoor PCB defect

A3 Indoor Malfunction of drain Level control system

A5 Indoor Freeze-up prevention

A6 Indoor Fan motor lock – overload

A7 Indoor Malfunction of swing motor flap

A9 Indoor Malfunction of EEV

AF Indoor Drain level above limit – clogged

AJ Indoor Malfunction of capacity set device

C3 Indoor Malfunction of drain thermistor

C4 Indoor Malfunction of liquid pipe thermistor

C5 Indoor Malfunction of gas pipe thermistor

C7 Indoor Lower louvre limit switch – motor

C9 Indoor Malfunction of air thermistor

CC Indoor Malfunction of moisture sensor

CA Indoor Malfunction of discharge air thermistor

CJ Indoor Malfunction of remote control thermistor

CE Indoor Malfunction of radiant heat sensor

E0 Outdoor Activation of outdoor safety device

E1 Outdoor PCB defect

E3 Outdoor Activation of high pressure switch

E4 Outdoor Activation of low pressure switch

E5 Outdoor Activation of compressor over heat protection

E5 Outdoor Compressor motor lock

E6 Outdoor Compressor start up error

E6 Outdoor Standard compressor lock overcurrent

E7 Outdoor Fan motor lock – Overload

E8 Outdoor Inverter input overcurrent

E9 Outdoor Malfunction of EEV

EA Outdoor Four way valve defective

F3 Outdoor Abnormal discharge pipe temperature

F6 Outdoor Refrigerant overcharged

FC Outdoor Low pressure drop

H3 Outdoor High pressure switch defect

H4 Outdoor Low pressure switch defect

H6 Outdoor Compressor motor position detection sensor error

H7 Outdoor Fan motor position detection sensor error

H8 Outdoor Current transformer error

H9 Outdoor Malfunction of air thermistor

J1 Outdoor Faulty/Fault of pressure sensor

J2 Outdoor Current sensor Faulty/Fault

J3 Outdoor Faulty/Fault of discharge pipe thermistor

J4 Outdoor Low pressure saturation thermistor

J5 Outdoor Faulty/Fault of suction pipe thermistor

J6 Outdoor Faulty/Fault of heat exchanger thermistor

J7 Outdoor Faulty/Fault of heat exchanger liquid thermistor

J8 Outdoor Faulty/Fault of liquid pipe thermistor

J9 Outdoor Faulty/Fault of gas pipe thermistor

JA Outdoor Faulty/Fault of discharge pipe pressure sensor

JC Outdoor Faulty/Fault of suction pipe pressure sensor

JH Outdoor Faulty/Fault of oil temperature sensor

L0 Outdoor Malfunction of inverter

L3 Outdoor Electronic component box overheat

L4 Outdoor Inverter cooling defect

L5 Outdoor Comp motor ground fault Short circuit

L6 Outdoor Compressor motor grounding short circuit

L7 Outdoor Total input overcurrent

L8 Outdoor Comp overload – Motor disconnected

L9 Outdoor Compressor lock

LA Outdoor Power unit malfunction

LC Outdoor Transmission between inverter and outdoor

P1 Outdoor Inverter over ripple

P3 Outdoor Thermistor abnormality

P4 Outdoor Power unit humidity sensor malfunction

PJ Outdoor Failure of capacity set resistor

U0 System Shortage of refrigerant or EEV failure

U1 System Negative phase, Open phase

U2 System Power supply insufficient

U3 System Wiring check operation not executed

U3 System Mismatch of indoor and outdoor units – Split only

U4 System Transmission between indoor units

U5 System Transmission to remote controller

U6 System Malfunction transmission outdoor to BP unit

U7 System Transmission between outdoor units

U8 System Transmission between master and slave RC

U9 System Transmission error between indoor to outdoor

UA System Excessive number of fan coils

UC System Address duplication of central controllers

UE System Transmission error between indoor and central

UF System Refrigeration system not set wiring – piping

UF System Terminals 1 and 3 crossed (Split Skyair)

UH System Error with Refrigeration system set up

Fujitsu

00 Communication error (indoor unit to remote controller)

01 Communication error (indoor unit to outdoor unit)

02 Room temperature sensor

03 Room temperature sensor short-circuited

04 Indoor heat exchanger temperature sensor open

05 Indoor heat exchanger temperature sensor short-circuited

06 Outdoor heat exchanger temperature sensor open

07 Outdoor heat exchanger temperature sensor short-circuit

08 Error contents = Power source connection error

09 Float switch operated

0A Outdoor temperature sensor open

0b Outdoor temperature sensor short-circuited

0c Discharge pipe temperature sensor open

0d Discharge pipe temperature sensor short-circuited

0E Outdoor high pressure abnormal

0F Discharge pipe temperature abnormal

11 Model abnormal

12 Indoor fan abnormal

13 Outdoor signal abnormal

14 Outdoor EEPROM abnormal

OUTDOOR UNIT LEDS When the outdoor temperature drops, the outdoor units fans may switch to low speed.

LG

CH01 Indoor unit return air sensor fault.

CH02 Indoor Pipe Sensor or Outdoor Sensor Assembly fault, Open or Short.

CH03 Remote controller comms error. Check wired correctly, if so check dipswitch in RC. Set to Sg for 1 unit, or Gr for group then reset power.

CH04 RAC Product = Heat Sink Sensor Error, Open/Short Circuit or over 95C. Commercial Product = Condensate pump float switch risen. Check drain pan is empty, check pump is working OK. If no pump check blue jumper plug is inserted in socket CN Float.

CH05 Comms Error, check your wiring, remove external pumps. Split/Multi – check volts from terminal N to 3 = 0 – 65 Vdc, Multi V – 4 Vdc terminals 3 and 4.

CH06 Indoor unit coil sensor fault.

CH07 Multi Splits and Multi V = indoor unit is set to run in a different mode from the master indoor unit. Set ALL indoor units to cooling or ALL to heating to clear. Splits = Compressor Over Current (CT2), also see Code 06.

RAC Indoor unit BLDC Fan problem. This is caused by the Indoor fan being locked. Check fan motor is plugged in correctly, Electrically & Mechanically sound.

CH08 Check the fan motor turns freely, check the AC Voltage supplied to the fan motor, this will vary from 120 V ac at low speed to 170V AC at high speed. If no voltage is present the PCB is faulty, if voltage is present the fan motor will be faulty.

CH09 Split = Outdoor unit fan problem. Check Outdoor fan motor is plugged in, Electrically & Mechanically sound, if not replace motor, otherwise replace PCB. Multi V = indoor PCB failure. Replace PCB.

CH10 RAC Product: Compressor discharge sensor fault.

CH11 Multi V indoor unit not connected to an outdoor unit. Check comms wiring is correct, and check initialisation has been carried out correctly.

CH21 Inverter compressor run current high. Check compressor windings all equal 1 to 4 Ohms, check to earth 50 MOhm minimum.

CH22 Inverter compressor run current high. Check compressor windings all equal 1 to 4 Ohms . Check to earth 50 MOhm minimum.

CH23 Inverter dc voltage low. Check dc voltage of capacitors 300 Vdc for 1Ph and 600 Vdc for 3Ph. If OK change outdoor inverter PCB.

CH24 Splits and Multi Splits = High or low pressure trip.

CH25 Check power supply voltage to the outdoor unit is correct (1ph ?220 Vac ±10% or 3ph ?380 Vac ±10%). If OK, check fuses, if fuses are OK replace outdoor main PCB.

CH26 Inverter compressor seized.

CH27 Inverter current irregularity. Check inverter PCB and reactor.

CH28 Inverter dc voltage too high. Check dc voltage of capacitors 300 Vdc for 1Ph and 600 Vdc for 3Ph. If OK change outdoor inverter PCB.

CH32 Inverter compressor discharge temperature too high. If over 105°C, check refrigerant charge.

CH33 Excessive rise of standard compressor discharge temperature. If over 105°C check refrigerant charge.

CH34 Excessive high pressure rise.

CH35 Excessive low pressure drop under 1 Bar at LP sensor. Check pressures, and check service valves open.

CH40 Inverter ac current abnormal. Check compressor windings all equal resistance 1 to 4 Ohms, check to earth 50 MOhm minimum.

CH41 Inverter compressor discharge sensor fault.

CH42 Low pressure sensor fault. Check dc voltage between white and black cable on plug. Multi V: 1 Vdc = 4 bar up to 5 Vdc = 32 bar.

CH43 High pressure sensor fault. Check dc voltage between white and black cable on plug. Multi V: 1 Vdc = 8 bar up to 2.5 Vdc = 37 bar.

CH44 Outdoor unit air sensor fault.

CH45 Outdoor unit coil sensor fault.

CH46 Outdoor unit suction sensor fault.

CH47 Compressor discharge sensor fault.

CH48 Split/Multi Split = Outdoor unit discharge and air sensor both unplugged.

CH49 Check power supply voltage to the outdoor unit is correct (1ph = 220 Vac ±10% or 3ph = 380 Vac ±10%). If OK check fuses, if fuses OK, replace outdoor main PCB.

CH52 Communication error between inverter PCB and main outdoor unit PCB. Check wiring fuses and LEDs . If OK either inverter or main PCB defective.

CH53 Comms error indoor to outdoor unit. Check your wiring . Split and Multi – check voltage from terminal N to 3 = 0 – 65 Vdc, Multi V – 4 Vdc terminals 3 and 4.

CH54 Reverse or open phase.

CH57 Comms error between outdoor main PCB and inverter PCB. Check wiring fuses and LEDs are lit. If OK either inverter or main PCB defective.

CH60 Outdoor unit PCB EEPROM failure, try removing EEPROM and refitting if removable (possible contact fault), otherwise replace PCB if the EEPROM is non-removable.

CH61 Condenser coil over 65°C.

CH62 Inverter over 85°C. Check air flow across heat sink, check inverter tight to heatsink use thermal paste.

CH65 Outdoor unit inverter fin temperature sensor fault.

CH67 Outdoor Fan Motor seized, or rotation sensing circuit failure.

CL Child Lock. Press Timer & Min buttons simultaneously for 5 seconds to engage/disengage function.

HL Condensate pump float switch risen. Check drain pan is empty, check pump is working OK. If no pump check blue jumper plug is inserted in socket CN Float. Alternatively, Dry Contact Interface is in “OFF” condition. Check status and adjust as necessary.

Po Jet Cool Mode selected. To cancel press Jet Cool, Fan Speed or Set Temperature button.

Mitsubishi Electric

E1 The remote controller wire Y is open. The remote controller wires X and Y are reversely connected. Noise is penetrating the remote control lines. The remote controller or indoor control PCB is faulty.

E5 Indoor / outdoor transmission error. Outdoor unit control PCB is faulty when the power is turned on, or the inverter parts are faulty (FDCVA 151~251 type).

E6 Indoor unit heat exchanger thermistor failure.

E7 Indoor unit return air thermistor failure.

E8 Heating overload (indoor heat exchanger temperature is abnormally high) and indoor heat exchanger thermistor is faulty.

E9 The float SW operates (with FS only). Drain up kit wiring fault.

E10 When multi-unit control by remote controller is performed, the number of units is over (more than 17 units).

E16 Fan motor is faulty (FDTA 501, 601 type, FDKN type).

E28 Remote controller thermistor failure.

E32 Wiring is open or reversal phase (FDCA 301~601 type).

E33 Inverter primary side current is abnormal. (FDCVA151~251 type). Abnormal current cut of compressor (FDCA 301~601 type).

E34 52C secondary side L3-phase wiring is open. (FDCA 301~601 type).

E35 Outdoor heat exchanger temperature is high or outdoor heat exchanger thermistor is faulty.

E36 Discharge temperature abnormality.

E37 Outdoor unit heat exchanger thermistor failure.

E38 Outdoor air temperature thermistor failure.

E39 Discharge pipe thermistor failure.

E40 63H1 operation (FDCA 301~601 type).

E42 Current (Abnormalities in a compressor over current).

E47 Inverter Over-voltage Trouble. (FDCVA 151~251 type).

E48 DC fan motor abnormal. (FDCVA 151~251 type).

E52 52C abnormal. (FDCA 301~601 type).

E56 Power transistor thermistor is faulty or disconnection or connector connections are poor. (FDCVA 151~251 type).

E57 Insufficient refrigerant.

E59 Compressor start-up error (FDCVA 151~251 type).

E60 Compressor loader position detection error. (FDCVA 151~251 type).

Panasonic

S01 Room temperature sensor failure.

S02 Indoor coil sensor failure.

S03 Humidity sensor failure Replace indoor board.

S04 Comp. temperature sensor failure.

S05 Outdoor coil sensor failure.

S06 Outdoor air sensor failure.

S07 Outdoor current sensor failure. Replace outdoor board.

E01 Indoor/outdoor communication failure.

E02 HIC circuit failure (Compressor/Fan circuit).

E03 Outdoor unit OTP rom failure.

E04 Peak current cut off.

E05 PAM or Active circuit failure.

E06 High compressor discharge temperature.

E07 Indoor fan operating failure.

E08 4 way valve switching failure (RV).

E09 No refrigerant protection.

E10 DC compressor drive circuit failure.

E11 Outdoor fan operating failure.

E12 Error in outdoor unit.

E13 Freeze prevention activated.

H00 No abnormality detected.

H11 Indoor / Outdoor abnormal communication. > 1 min after starting operation. Indoor fan operation only • Internal / external cable connections. • Indoor / Outdoor PCB.

H12 Connection capability rank abnormal.

H14 Indoor intake air temperature sensor abnormality. Continue for 5 sec. Intake air temperature sensor (detective or disconnected).

H15 Outdoor compressor temperature sensor abnormality. Continue for 5 sec. Compressor temperature sensor (detective or disconnected).

H16 Outdoor Current Transformer open circuit. Outdoor PCB or IPM (Power transistor) module.

H19 Indoor fan motor mechanism locked. 7 times occurrence continuously. Indoor PCB or/and Fan motor.

H23 Indoor heat exchanger temperature sensor abnormality. (Cooling only) Heat exchanger temperature sensor (detective or disconnected).

H24 Indoor heat exchanger temperature sensor 2 abnormality. Continue for 5 sec. Heat exchanger temperature sensor (detective or disconnected).

H27 Outdoor intake air temperature sensor abnormality. Continue for 5 sec. Outdoor temperature sensor (detective or disconnected).

H28 Outdoor heat exchanger temperature sensor abnormality. Continue for 5 sec. Outdoor heat exchanger temperature sensor (detective or disconnected).

H30 Outdoor discharge air temperature sensor abnormality Continue for 5 sec. Outdoor temperature sensor (detective or disconnected).

H33 Indoor / Outdoor wrong connection. Indoor / Outdoor supply voltage.

H38 Indoor / Outdoor mismatch (brand code).

H50 Ventilation motor abnormality. 7 times occurrence continuously. Indoor PCB / Ventilation motor.

H51 Nozzle lock abnormality. 2 times occurrence continuously.

H52 Limit switch abnormality. Indoor PCB.

H97 Outdoor fan motor mechanism locked. 2 times occurrence within 30 minutes. Indoor PCB / Fan motor.

H98 Indoor high pressure protection . Air filter dirty.

H99 Indoor heat exchanger anti-freezing protection. Insufficient refrigerant or Air filter dirty.

F11 Cooling / Heating cycle changeover abnormality. 4 times occurrence within 30 minutes. 4-way valve/ V-coil.

F90 PFC control. 4 times occurrence within 10 minutes. Voltage at PFC.

F91 Refrigeration cycle abnormality. 2 times occurrence within 20 minutes. No refrigerant (3-way valve is closed).

F93 Compressor rotation failure. 4 times occurrence within 20 minutes. Compressor failure.

F95 Cool high pressure protection. 4 times occurrence within 20 minutes. Outdoor refrigerant circuit.

F96 IPM (power transistor) overheating protection. 4 times occurrence within 30 minutes. Excess refrigerant/ Improper heat radiation / IPM (Power transistor).

F97 Outdoor compressor overheating protection. 4 times occurrence within 10 minutes. Insufficient refrigerant / Compressor.

F98 Total running current protection. 3 times occurrence within 20 minutes. Excess refrigerant / Improper heat radiation.

F99 Outdoor Direct Current (DC) peak detection. 7 times occurrence continuously. Outdoor PCB/ IPM (Power transistor) / Compressor.

 

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