Hitachi air conditioner error codes

Being a part of the DKB Group, Hitachi in its own turn, is a parent company of the Hitachi Group. The Japanese conglomerate company produces goods in more than ten segments, from electronics and information systems to railway and automotive systems. It is listed in the Forbes rankings of the world’s most influential companies on a regular basis.

Sometimes, error codes can give you enough information to fix your Hitachi air conditioner on your own. However, in most cases the help of a service engineer is indispensible. Anyway, the fault code will help you to find out what the problem is and decide whether you can deal with it on your own. The table below contains the error codes for Hitachi air conditioning systems, explained in all details.

Hitachi Inverter-driven Multi-Split system heat pump Air Conditioner

Code No.CategoryContent of AbnormalityLeading Cause
01Indoor UnitTripping of Protection DeviceFailure of Fan Motor, Drain Discharge, PCB, Relay
02Outdoor UnitTripping of Protection DeviceActivation of PSH
03TransmissionAbnormality between Indoor (or outdoor) and

Outdoor (or Indoor)
Incorrect Wiring. Failure of PCB.

Tripping of Fuse. Power Supply OFF.
04InverterAbnormality between Inverter and Control PCBFailure in Transmission between PCBs
05TransmissionAbnormality of Power Source WiringReverse Phase Incorrect Wiring
06Voltage DropVoltage Drop by Excessively Low or High

Voltage to Outdoor Unit
Voltage Drop of Power Supply, Incorrect Wiring or

Insufficient Capacity of Power Supply Wiring
07CycleDecrease in Discharge Gas SuperheatExcessive Refrigerant Charge, Expansion Valve

Open Lock
08CycleIncrease in Discharge Gas TemperatureInsufficient Refrigerant. Ref. Leakage, Clogging or

Expansion Valve Close Lock
09Outdoor UnitTripping of Protection DeviceFailure of Fan Motor
11Sensor on Indoor UnitInlet Air ThermistorFailure of Thermistor, Sensor, Connection
12Sensor on Indoor UnitOutlet Air ThermistorFailure of Thermistor, Sensor, Connection
13Sensor on Indoor UnitFreeze Protection ThermistorFailure of Thermistor, Sensor, Connection
14Sensor on Indoor UnitGas Piping ThermistorFailure of Thermistor, Sensor, Connection
19Sensor on Indoor UnitTripping of Protection Device for Fan MotorFailure of Fan Motor
21Sensor on Outdoor UnitHigh Pressure SensorFailure of Thermistor, Sensor, Connection
22Sensor on Outdoor UnitOutdoor Air ThermistorFailure of Thermistor, Sensor, Connection
23Sensor on Outdoor UnitDischarge Gas Thermistor on Comp.Failure of Thermistor, Sensor, Connection
24Sensor on Outdoor UnitEvaporating ThermistorFailure of Thermistor, Sensor, Connection
29Sensor on Outdoor UnitLow Pressure SensorFailure of Thermistor, Sensor, Connection
30 *SystemIncorrect Wiring ConnectionIncorrect Wiring Connection between Outdoor Unit,

CH Unit and Indoor Unit
31SystemIncorrect Setting of Outdoor and Indoor UnitIncorrect Setting of Capacity Code.
32SystemAbnormal Transmission of Other Indoor UnitFailure of Power Supply, PCB in Other Indoor Unit.

Failure of Other Indoor Unit of the Same

Refrigerant Cycle.
35SystemIncorrect Setting in Indoor/Outdoor Unit No.Existence of the same Indoor Unit No. in the same

refrigerant cycle.
38SystemAbnormality of Protective Circuit in

Outdoor Unit
Failure of Indoor Unit PCB. Incorrect Wiring

Connection to PCB in Outdoor Unit
39SystemAbnormality of Running Current at

Constant Compressor
Overcurrent, Melted Fuse of Failure of Current

43PressurePressure Ratio Decrease Protection ActivatingFailure of Compressor, Inverter
44PressureLow Pressure Increase Protection ActivatingOverload to Indoor in Cooling, High Temperature of

Outdoor Air in Heating Expansion Valve Open Lock
45PressureHigh Pressure Increase Protection ActivatingOverload Operation. Excessive Refrigerant

Clogging of Heat Exchanger
46PressureHigh Pressure Decrease Protection ActivatingInsufficient Refrigerant
47PressureLow Pressure Decrease Protection ActivatingInsufficient Refrigerant. Expansion Valve Close

Lock. Refrigerant Leakage.
51InverterAbnormality of Current Sensor for InverterFailure of Sensor on Inverter PCB
52InverterOvercurrent Protection ActivatingOverload, Overcurrent, Locked to Compressor
53InverterIPM Protection ActivatingAutomatic Stoppage of IPM (Overcurrent, Low

Voltage or Overheating)
54 **InverterIncrease in Inverter Fin TemperatureAbnormal Inverter Fin Thermistor,

Abnormal Outdoor Fan
56 **Outdoor FanAbnormality of Detection for Fan Motor PositionAbnormal Detection Circuit of Transmission
57 **Outdoor FanFan Controller Protection ActivatingAbnormal Fan Speed
58 **Outdoor FanAbnormality of Fan ControllerOvercurrent, Abnormal Fan Controller Fin
59AC ChopperAC Chopper Circuit ProtectionFailure of FET, Power Supply, CT for Fan Motor
EECompressorCompressor Protection3 Time Occurrence of Alarm Giving Damage to

Compressor within 6 hours
dd ***TransmissionIncorrect Wiring between Indoor UnitsIncorrect Wiring between Indoor Units and Remote

Control Switch

* : For only FXG and FX3 series. Other code Nos. are common with FSG and FS3 series.

** : For only 24, 30FSG1/FSG5 (220V 60Hz), *** : In case of PC-2H2

Room Air Conditioner range:

Indoor unit alarm codes

If timer lamp flashes for 1 second on, 1 second off, this indicates pre heating on the coil during heating mode and is not an error.

If timer lamp flashes for a number of times and then pauses, please reference table below. Display will flash as shown in diagram.

LED 301 FlashesRange: Summit/Mono/Multizone indoor unit
01Indoor coil is too warm in cooling mode or too cold in heating mode.

Reversing valve or coil thermistor is faulty
02Forced operation from the outdoor unit.

This is not an error
03Communication error.

Faulty wiring, indoor or outdoor PCB faulty
04Outdoor unit fault.

Check the number or flashes on outdoor PCB LED 301 to comfirm exact problem
06Float switch activated.

Check pump operation and drain
07Drain pump forced operation.

Drain test switch in test position, faulty PCB
08Louvre not opening.

Louvre motor faulty, microswitch faulty, PCB faulty (RAF unit only)
09Faulty indoor unit thermistor.

Air inlet or coil thermistor not connected, open or short circuited faulty PCB
10Indoor fan motor over current or abnormal rotation speed.

Faulty motor or PCB
13Eprom data error.

Faulty PCB

Room Air Conditioner range:

Outdoor unit alarm codes

LED 301 FlashesRange: Summit/Mono/Multizone outdoor unit
1Normal, unit powered up
2Over current on the compressor

Faulty PCB or locked compressor

with LED302 lit
Over current on the compressor

System power module or PCB failure
3Compressor rotation speed is low, abnormal compressor rotor position

Faulty system power module, faulty compressor or PCB
4Switching failure on the compressor

Faulty system power module, faulty compressor or PCB
5Compressor rotation low with over current detected

High pressure detected, faulty fan motor/circuit or abnormally low voltage
6Discharge thermistor temperature rising

Short of refrigerant charge, faulty thermistor, faulty compressor faulty fan motor/circuit or main PCB
7Faulty thermistor (Summit and Monozone only)
8Compressor not accelerating above minimum rotation speed

Short of refrigerant charge or faulty compressor
9Communication error

C/D terminals not connected, faulty interconnecting cable PCB failure (Summit and Monozone only)
10Abnormal voltage

Mains voltage incorrect or faulty reactor
12Fan motor rotation is abnormal

Faulty fan motor or PCB (check fuse)
13Eprom error

Main PCB failure
14Over voltage is detected by system power module

Faulty SPM

If indoor unit filter lamp is flashing four times, this indicates an outdoor unit fault. This is identified by the number of flashes on LD 301, please see the table right.

If LD 303 is on permanently this is normal operation. If LD 301 is lit in conjunction with LD 303 his indicates an overload (1) condition but not an alarm. If LD 302 is lit in conjunction with LD 303 this indicates an overload (2) condition but not an alarm and if LD 301 and LD 302 are lit in conjunction with LD 303, this indicates an overload (3) condition but not an alarm.

On Multizone systems only, if LD 301 is lit permanently and LD 302 is flashing a number of times, this indicates a thermistor fault. Please refer to the table right for the thermistor that is faulty. If LD 304 is flashing, the number of flashes indicates a communication error with the corresponding indoor unit circuit number. Check cable connections, cable is not short circuited or open circuit and PCB operation.

LD 302 FlashesFlashesThermistor that is faulty
1Compressor overheat (OH)
2Defrost thermistor
3Ambient thermistor
4Narrow pipe (expansion) thermistor, for circuit 1
5Wide pipe (suction) thermistor, for circuit 1
6Narrow pipe (expansion) thermistor, for circuit 2
7Wide pipe (suction) thermistor, for circuit 2
8Narrow pipe (expansion) thermistor, for circuit 3
9Wide pipe (suction) thermistor, for circuit 3

Heat Pump

If a Safety Device is activated, cutting out the compressor, the Run light on the Remote Control switch blinks continuously and ABNML is indicated on the LCD display.
The Unit Identification A* etc is shown along with the Code Number for the Fault that has occurred.

Fault CodeLED1LED2LED3LED4Fault
02*Safety Device (Indoor or Outdoor Unit)
03*Transmission Indoor/Outdoor Unit
08***Compressor High Temperature
20**Compressor Thermistor
22**Ambient Air Thermistor
24**Defrost Thermistor
38**PCB Protection Circuit
41**Overload Operation for Cooling
42***Overload Operation for Heating
11-13****11 Fault = Air Inlet Thermistor

13 Fault = Freeze Protection Thermistor