Acson air conditioner error codes

Your acson aircon light blinking and you are searching for the error codes? AC light blinking usually indicate you have to service your aircon or the ac circuit board have problem that requires immediately attention.

Acson rooftop packaged air conditioner ( Multi Compressors ) error codes

How to check error codes?

When the system is on and an error occurs, the ON/OFF LED on the LCD panel will blink and an error code is shown. When the system is off and there is a thermistor error, the ON/OFF LED is off but the error code is still displayed. Each error code represents different message as below.

Error codePossible cause
E01Require manual reset
E02Compressor 1 high temperature
E03Compressor 2 high temperature
E04Compressor 3 high temperature
E05Compressor 4 high temperature
E06Compressor 1 high pressure trip / contact open
E07Compressor 2 high pressure trip / contact open
E08Compressor 3 high pressure trip / contact open
E09Compressor 4 high pressure trip / contact open
E10Compressor 1 trip / low refrigerant / outdoor abnormal
E11Compressor 2 trip / low refrigerant / outdoor abnormal
E12Compressor 3 trip / low refrigerant / outdoor abnormal
E13Compressor 4 trip / low refrigerant / outdoor abnorma
E14Room sensor short
E15Room sensor open
E16Indoor coil sensor 1 short
E17Indoor coil sensor 2 short
E18Indoor coil sensor 3 short
E19Indoor coil sensor 4 short
E20Indoor coil sensor 1 open
E21Indoor coil sensor 2 open
E22Indoor coil sensor 3 open
E23Indoor coil sensor 4 open
E24Outdoor coil sensor 1 short
E25Outdoor coil sensor 2 short
E26Outdoor coil sensor 3 short
E27Outdoor coil sensor 4 short
E28Outdoor coil sensor 1 open
E29Outdoor coil sensor 2 open
E30Outdoor coil sensor 3 open
E31Outdoor coil sensor 4 open
E32Compressor 1 de-ice
E33Compressor 2 de-ice
E34Compressor 3 de-ice
E35Compressor 4 de-ice

Acson inverter-y indoor series air conditioner error codes

How to diagnosis error code using wireless handset G18?

How to diagnosis acson ac error code using wireless handset G18
  1. Hold down TIMER CANCEL button for 5 seconds, a “00 ” indication flashes on the
    temperature display section.
  2. Press TIMER CANCEL repeatedly until indoor buzzer produces a long beep. This indicates the error code, refers to Error Codes table and is displayed on the temperature display section.
  3. A short beep or two consecutive beeps indicate non-corresponding error codes.
  4. To cancel the error code display, hold down TIMER CANCEL button for 5 seconds.
    Alternatively, the code display will cancel itself if the button is not pressed for 1 minute
Error codePossible cause
U0Insufficient gas
U2DC voltage out of range
U4Communication error
U7Signal transmission error (on outdoor unit PCB)
UAInstallation error
UFCommunication Error (indoor and outdoor) piping and wiring
UHAnti-freeze function in other room
A1Indoor PCB error
A3Water pump error
A6Indoor fan motor abnormal
C4Indoor heat exchanger thermistor short/ open
C9Indoor room thermistor short/ open
E1Outdoor PCB error
E3High pressure protection
E4Low pressure protection
E5Compressor motor lock
E6Compressor start-up error
E7Outdoor DC fan motor lock
E8Ac input over current
E9EXV error
EA4-way valve error
F3Discharge pipe overheat
F6Heat exchanger overheat
H0Compressor sensor system abnormality
H3High pressure switch error
H6Position sensor abnormality
H8AC current sensor error
H9Outdoor air thermistor short / open
J1Pressure sensor error
J3Compressor discharge pipe thermistor short /open / misplaced
J5Suction pipe thermistor short/ open
J6Outdoor heat exchanger
J7Subcooling heat exchanger thermistor short/ open
J8Liquid pipe thermistor short/ open
J9Gas pipe thermistor abnormality
LCCommunication error (control PCB and inverter PCB)
L1Outdoor PCB error
L3Electrical box temperature rise
L4Heat sink overheat
L5IPM error / IGBT error
L8Electrical thermal switch
L9Stall prevention
P1Open phase or voltage unbalance
P4Heat sink thermistor short / open
PJCapacity setting error

Acson wall mounted K-Series inverter air conditioner error codes

The operation lamp flashes when any of the following errors is detected.

acson ac error code Indoor LED Indication
  1. When a protection device of the indoor or outdoor unit is activated or when the thermistor malfunctions, disabling equipment operation.
  2. When a signal transmission error occurs between the indoor and outdoor units.

How to diagnosis error code using wireless handset APJ2?

How to diagnosis error code using wireless handset APJ2
  1. When the CANCELL button is held down for 5 seconds, a indication blinks on the temperature display section.
  2. Press the CANCELL button repeatedly until a continuously beep is produced.
Error codePossible cause
UAIndoor-outdoor unit combination fault
U0Refrigerant shortage
U2Drop voltage or main circuit overvoltage
U4Failure of transmission ( between indoor unit and outdoor unit)
A1Indoor PCB defectiveness
A5High pressure control or freeze-up protector
A6Fan motor fault
C4Faulty heat exchanger temperature sensor
C9Faulty suction air temperature sensor
EACooling-heating switching error
E1Circuit board fault
E5Ol started
E6Faulty compressor start up
E7DC fan motor fault
E8Overcurrent input
F3High temperature discharge PPE control
F6High pressure control ( in cooling )
H0Sensor fault
H6Operation fault due to faulty position detection sensor
H8DC current sensor fault
H9Faulty suction air temperature sensor
J3Faulty discharge pipe temperature sensor
J6Faulty heat exchanger temperature sensor
L3Electrical parts heat fault
L4High temperature at inverter circuit heatsink
L5Output overcurrent
P4Faulty inverter circuit heatsink temperature sensor


  1. A short beep and 2 consecutive beeps indicate non-corresponding codes.
  2. To cancel the code display, hold the CANCELL button down for 5 seconds. The code display also cancels itself if the button is not pressed for 1 minute.

Acson air conditioner general troubleshooting guide

When any air conditioner malfunction is noted, immediately switch off the power supply to the unit and
contact the local dealer if necessary.

Problem SymptomCheck ItemSuggested Action
The unit does not workCheck the power supplyCheck to make sure that the rated voltage is supplied
Check the fuseCheck and replace the fuse
Check the remote controller timer settingMake sure the delay timer is set correctly
Fan does not workCheck the power supplyCheck to make sure that the rated voltage is supplied
Check the fan motor capacitorCheck and replace the capacitor
Check the fan motorCheck and replace the fan motor
Check the switchCheck and change the switch
Fan work, but compressor does not workCheck if the thermostat setting too highReset thermostat
Check the compressor capacitorCheck and replace the capacitor
Check the compressorCheck and replace the compressor
Check the compressor contactorCheck and replace the contactor
Air conditioner work but cooling not
Check if the thermostat setting too highReset thermostat
Check if the condenser coil dirtyClean the condenser coil
Check the condenser installation conditionMake sure the condenser is installed according to factory’s recommendation
Diagnosis by service port pressure and operating CurrentCheck for insufficient refrigerant
The air flow is too lowCheck the air filterCheck and make sure the air filter is clean
Check the fan / blower conditionCheck and make sure that the fan / blower are in good condition
The remote controller Check and replace the battery. light is dimCheck the batteryCheck and replace the battery

Acson aircon diagnostic flows chart

Generally, there are two kinds of problems, i.e. starting failure and insufficient cooling/ heating. “Starting failure” is caused by electrical defect while improper application or defects in refrigerant circuit causes “insufficient cooling/ heating”.

Diagnosis of Electric circuit

acson aircon diagnosis of Electric circuit

The most common causes of air conditioner failure to ‘start’ are:

  • Voltage not within ± 10% of the rated voltage.
  • Power supply interrupted
  • Improper control settings
  • Air conditioner is disconnected from main power source
  • Fuse blown or circuit breaker off.

Diagnosis of Refrigerant Circuit/ Application

There might be some causes where the unit starts to run but does not perform satisfactorily, example, insufficient cooling. Judgement could be made by measuring temperature difference of indoor unit’s intake and discharge air as well as running current.

acson aircon Diagnosis of Refrigerant Circuit