Inverter AC Error Codes
Fault code database for VRF and mini-split systems
Found 214 error codes
Daikin
Japan • 30 error codes
| Code | Description | Cause | Action |
|---|---|---|---|
| A0 | External protection device activated | External protection relay triggered | Check external protection device, reset if safe |
| A1 | Indoor PCB defect | Indoor unit control board failure | Replace indoor PCB |
| A3 | Drain level abnormal | Condensate drain blocked or float switch activated | Clean drain line, check float switch |
| A5 | Heat exchanger freeze-up | Evaporator coil freezing | Check airflow, refrigerant charge, expansion valve |
| A6 | Fan motor abnormal | Indoor fan motor locked or abnormal | Check fan motor, capacitor, wiring |
| A7 | Swing motor abnormal | Louver/swing motor failure | Check swing motor and drive circuit |
| C4 | Heat exchanger sensor fault | Indoor coil thermistor open/short | Check thermistor resistance, replace if out of spec |
| C9 | Room temperature sensor fault | Room temperature thermistor failure | Check sensor connection and resistance |
| E0 | External protection device | Outdoor external protection activated | Check external protection circuit |
| E1 | Outdoor PCB fault | Outdoor control board failure | Replace outdoor PCB |
| E3 | High pressure switch activated | High discharge pressure | Check condenser, fan, refrigerant charge, ambient |
| E4 | Low pressure switch activated | Low suction pressure | Check refrigerant charge, expansion valve, airflow |
| E5 | Inverter compressor overload | Compressor motor overcurrent | Check compressor, power supply, refrigerant |
| E6 | Standard compressor overload | Fixed speed compressor overcurrent | Check compressor, capacitor, power supply |
| E7 | Fan motor overcurrent | Outdoor fan drawing excess current | Check fan motor, blade, bearings |
| E9 | Electronic expansion valve fault | EEV driver or valve failure | Check EEV wiring, driver, replace valve if needed |
| F3 | Discharge pipe temperature high | Compressor discharge overheating | Check superheat, refrigerant charge, airflow |
| F6 | High pressure abnormal | Pressure sensor detecting high pressure | Check refrigerant charge, condenser, ambient |
| H6 | Position sensor fault | Compressor position sensor failure | Check sensor wiring, replace compressor if internal |
| H8 | CT sensor fault | Current transformer failure | Check CT sensor and wiring |
| H9 | Outdoor air sensor fault | Outdoor ambient thermistor failure | Check thermistor resistance and connection |
| J3 | Discharge pipe sensor fault | Discharge temperature thermistor failure | Replace discharge temperature sensor |
| J6 | Heat exchanger sensor fault | Outdoor coil thermistor failure | Check thermistor, replace if needed |
| L3 | Electrical box temperature high | Control box overheating | Check ventilation, clean control box |
| L4 | Heat sink temperature high | Inverter heat sink overheating | Check airflow around outdoor unit |
| L5 | Compressor overcurrent | Instantaneous overcurrent trip | Check compressor, wiring, voltage |
| P4 | Inverter heat sink sensor fault | Heat sink thermistor failure | Replace heat sink temperature sensor |
| U0 | Low refrigerant | System undercharged | Check for leaks, recharge system |
| U2 | Abnormal power supply voltage | Low or high voltage detected | Check power supply voltage, connections |
| U4 | Communication error | Indoor-outdoor communication failure | Check communication wiring, connectors |
Mitsubishi Electric
Japan • 29 error codes
| Code | Description | Cause | Action |
|---|---|---|---|
| E0 | Remote controller signal error | Communication issue with remote | Check remote controller and receiver |
| E1 | Remote controller PCB error | Remote control board fault | Replace remote controller |
| E3 | Communication error | No communication between units | Check wiring between indoor and outdoor |
| E6 | Indoor/outdoor communication error | Serial communication failure | Check S21/S22 communication lines |
| E7 | Indoor fan motor error | Fan motor failure | Check fan motor, hall sensor, connections |
| E9 | Indoor/outdoor communication error | Communication timeout | Check wiring polarity and connections |
| Eb | Indoor PCB error | Indoor control board failure | Replace indoor PCB |
| F1 | Room thermistor open/short | Room temperature sensor fault | Check/replace room thermistor |
| F2 | Indoor coil thermistor fault | Evaporator sensor open/short | Check/replace coil thermistor |
| P1 | Power supply peak detection | Input voltage variation | Check power supply stability |
| P2 | Current sensor error | CT sensor failure | Check CT sensor and wiring |
| P4 | Drain sensor error | Float switch activated | Clean condensate drain |
| P5 | Drain pump error | Condensate pump failure | Check drain pump operation |
| P6 | Freeze/overheat protection | Coil temperature abnormal | Check airflow, refrigerant charge |
| P8 | Pipe thermistor error | Liquid pipe sensor fault | Check pipe thermistor |
| P9 | Outdoor unit protection | Outdoor unit fault | Check outdoor unit error codes |
| U1 | High pressure switch | High pressure protection | Check condenser, refrigerant, airflow |
| U2 | Low pressure switch | Low pressure protection | Check refrigerant charge, filter |
| U3 | Short cycle | Compressor short cycling | Check timer settings, pressure |
| U4 | Discharge pipe temp high | Compressor overheat | Check refrigerant, airflow |
| U5 | Heat sink overheat | Inverter overheating | Check outdoor unit airflow |
| U6 | Compressor overcurrent | Compressor drawing excess current | Check compressor, voltage, refrigerant |
| U7 | Low superheat | Possible liquid flooding | Check expansion valve, charge |
| U8 | Outdoor fan error | Outdoor fan motor fault | Check fan motor, capacitor |
| U9 | Power voltage error | Input voltage out of range | Check power supply voltage |
| UA | Compressor overcurrent (CT) | Current transformer detected overcurrent | Check compressor, wiring |
| Ub | Outdoor coil thermistor error | Condenser sensor fault | Check/replace outdoor coil thermistor |
| Ud | Discharge thermistor error | Discharge sensor open/short | Check/replace discharge thermistor |
| UF | Compressor overcurrent (peak) | Instantaneous overcurrent | Check compressor, wiring, voltage |
LG
South Korea • 24 error codes
| Code | Description | Cause | Action |
|---|---|---|---|
| CH01 | Indoor room temp sensor error | Thermistor open/short | Check/replace room thermistor |
| CH02 | Indoor inlet temp sensor error | Evaporator inlet sensor fault | Check sensor connection and resistance |
| CH03 | Indoor outlet temp sensor error | Evaporator outlet sensor fault | Check/replace outlet thermistor |
| CH05 | Communication error | Wired remote communication fail | Check communication wiring |
| CH06 | Indoor outlet temp sensor error | Sensor fault | Check outlet pipe sensor |
| CH07 | Indoor BLDC motor error | Fan motor failure | Check BLDC motor, hall sensor |
| CH10 | Indoor BLDC motor error | Motor locked rotor | Check for obstructions, replace motor |
| CH21 | Outdoor DC link voltage error | DC bus voltage abnormal | Check power supply, inverter board |
| CH22 | Outdoor current detection error | CT sensor fault | Check CT sensor |
| CH23 | Outdoor DC link low voltage | Low DC bus voltage | Check power supply voltage |
| CH26 | Outdoor fan BLDC error | Outdoor fan motor fault | Check fan motor operation |
| CH27 | Outdoor PSC motor error | PSC fan motor fault | Check fan motor, capacitor |
| CH32 | Outdoor discharge temp high | Compressor overheat | Check refrigerant, airflow |
| CH33 | Outdoor discharge temp sensor error | Discharge thermistor fault | Check/replace sensor |
| CH34 | High pressure sensor error | Pressure transducer fault | Check pressure sensor |
| CH35 | Low pressure sensor error | Pressure transducer fault | Check pressure sensor |
| CH38 | Outdoor compressor temp sensor error | Compressor thermistor fault | Check sensor on compressor shell |
| CH40 | Outdoor CT sensor error | Current transformer fault | Check CT sensor and wiring |
| CH44 | Outdoor air temp sensor error | Ambient thermistor fault | Check/replace outdoor thermistor |
| CH45 | Outdoor condenser temp sensor error | Condenser thermistor fault | Check/replace coil thermistor |
| CH53 | Communication error between PCBs | Internal communication fault | Check outdoor PCB connections |
| CH61 | Outdoor condenser temp high | High condensing temperature | Clean condenser, check fan |
| CH62 | Inverter module temp high | IPM overheating | Check airflow around outdoor unit |
| CH67 | Outdoor fan motor lock | Fan motor locked | Check for obstructions, replace motor |
Samsung
South Korea • 19 error codes
| Code | Description | Cause | Action |
|---|---|---|---|
| E101 | Communication error | Indoor-outdoor communication fail | Check communication wiring |
| E121 | Indoor room sensor error | Room thermistor fault | Check/replace room sensor |
| E122 | Indoor coil sensor error | Evaporator thermistor fault | Check/replace coil sensor |
| E154 | Indoor fan error | Fan motor failure | Check fan motor, connections |
| E162 | Indoor EEPROM error | Memory chip fault | Replace indoor PCB |
| E201 | Communication error | Outdoor communication fault | Check wiring polarity |
| E221 | Outdoor TH1 sensor error | Outdoor coil sensor fault | Check/replace TH1 |
| E231 | Abnormal high pressure | High pressure detected | Check refrigerant, condenser |
| E237 | Inverter overcurrent | IPM overcurrent trip | Check compressor, wiring |
| E251 | Outdoor EEPROM error | Memory chip fault | Replace outdoor PCB |
| E416 | Compressor discharge temp high | Compressor overheat | Check refrigerant, superheat |
| E440 | Low pressure switch open | Low pressure protection | Check refrigerant charge |
| E441 | High pressure switch open | High pressure protection | Check condenser, charge |
| E461 | Compressor startup failure | Compressor failed to start | Check compressor, voltage, wiring |
| E464 | Compressor overcurrent | Excessive compressor current | Check compressor, refrigerant |
| E465 | DC link voltage error | DC bus voltage abnormal | Check power supply |
| E466 | Outdoor fan error | Fan motor fault | Check fan motor operation |
| E468 | CT sensor error | Current sensor fault | Check CT sensor |
| E554 | Inverter module temp high | IPM overheating | Improve ventilation |
Gree
China • 20 error codes
| Code | Description | Cause | Action |
|---|---|---|---|
| E1 | High pressure protection | High discharge pressure | Check condenser, fan, refrigerant |
| E2 | Indoor freeze protection | Evaporator freezing | Check airflow, charge, expansion valve |
| E3 | Low pressure protection | Low suction pressure | Check refrigerant charge, filter |
| E4 | Compressor discharge temp high | Compressor overheating | Check superheat, refrigerant |
| E5 | Overcurrent protection | Compressor overcurrent | Check compressor, voltage |
| E6 | Communication error | Indoor-outdoor communication fail | Check wiring connections |
| E7 | Mode conflict | Multi-split mode mismatch | Set all units to same mode |
| E8 | Overload protection | System overload | Check load, reduce demand |
| E9 | Full water protection | Condensate tank full | Empty condensate tank |
| F0 | Refrigerant shortage | Low refrigerant | Check for leaks, recharge |
| F1 | Indoor ambient sensor error | Room thermistor fault | Check/replace sensor |
| F2 | Indoor coil sensor error | Evaporator thermistor fault | Check/replace sensor |
| F3 | Outdoor ambient sensor error | Outdoor thermistor fault | Check/replace sensor |
| F4 | Outdoor coil sensor error | Condenser thermistor fault | Check/replace sensor |
| F5 | Discharge temp sensor error | Discharge thermistor fault | Check/replace sensor |
| F6 | Overcharge protection | System overcharged | Recover excess refrigerant |
| H1 | Defrost mode | Heat pump defrosting (normal) | Wait for defrost to complete |
| H3 | Compressor overload | Compressor thermal protection | Check compressor, charge |
| H5 | IPM protection | Inverter module fault | Check inverter board |
| H6 | Fan motor feedback error | Indoor fan motor fault | Check fan motor, connections |
Panasonic
Japan • 24 error codes
| Code | Description | Cause | Action |
|---|---|---|---|
| H00 | No abnormality | Normal operation | No action required |
| H11 | Communication error | Indoor-outdoor communication fail | Check communication wiring |
| H12 | Indoor unit capacity error | Capacity mismatch | Check system configuration |
| H14 | Indoor air sensor error | Room thermistor fault | Check/replace room sensor |
| H15 | Indoor compressor sensor error | Sensor fault | Check indoor sensors |
| H16 | Indoor current sensor error | CT sensor fault | Check CT sensor |
| H19 | Indoor fan motor error | Fan motor locked | Check fan motor operation |
| H23 | Indoor gas pipe sensor error | Thermistor fault | Check/replace gas pipe sensor |
| H25 | Indoor filter cleaning error | Auto-clean function error | Clean filter, check mechanism |
| H27 | Outdoor air sensor error | Ambient thermistor fault | Check/replace outdoor sensor |
| H28 | Outdoor coil sensor error | Condenser thermistor fault | Check/replace coil sensor |
| H30 | Outdoor discharge sensor error | Discharge thermistor fault | Check/replace discharge sensor |
| H33 | Connection mistake | Wiring connection error | Check indoor/outdoor wiring |
| H38 | Indoor/outdoor mismatch | Unit mismatch | Verify compatible units |
| H98 | Indoor high pressure protection | Indoor unit pressure high | Check airflow, filter |
| H99 | Indoor freeze protection | Evaporator freezing | Check airflow, charge |
| F11 | 4-way valve error | Reversing valve malfunction | Check 4-way valve coil, operation |
| F17 | Indoor freeze protection | Freezing detected | Defrost, check airflow |
| F90 | Outdoor inverter error | Inverter circuit fault | Check inverter board |
| F91 | Refrigerant cycle error | Refrigerant system fault | Check charge, valves, piping |
| F93 | Compressor rotor position error | Position sensor fault | Check compressor, inverter |
| F95 | Outdoor cooling error | Condenser performance issue | Clean condenser, check fan |
| F96 | IPM overheat | Inverter module overheating | Check ventilation, heat sink |
| F97 | Compressor overheat | Compressor overheating | Check refrigerant, superheat |
Hitachi
Japan • 36 error codes
| Code | Description | Cause | Action |
|---|---|---|---|
| 02 | High pressure protection | High pressure cut activated | Check refrigerant charge, condenser, fan operation |
| 03 | Indoor/outdoor communication error | Disconnected wires, loose terminals, incorrect wiring | Check communication wiring between units |
| 04 | Outdoor PCB to fan controller error | Blown fuse, loose connectors, broken wires | Check outdoor fan controller circuit |
| 06 | Phase detection failure | Phase sequence error or missing phase | Check 3-phase power supply, correct phase sequence |
| 0A | Outdoor to outdoor communication error | Damaged wiring, incorrect connections (multi-split) | Check wiring between outdoor units |
| 0B | Main unit address error | Multiple units set as main unit | Check address settings, set only one main |
| 0C | Sub unit address error | Address setting conflict | Correct address settings on sub units |
| 11 | Indoor inlet air thermistor error | Thermistor open/short circuit | Check/replace inlet air thermistor |
| 12 | Indoor outlet air thermistor error | Thermistor failure | Check/replace outlet air thermistor |
| 13 | Indoor freeze protection thermistor error | Evaporator thermistor fault | Check/replace evaporator thermistor |
| 14 | Indoor gas piping thermistor error | Gas pipe sensor failure | Check/replace gas pipe thermistor |
| 21 | Outdoor high pressure sensor error | Pressure transducer fault | Check/replace high pressure sensor |
| 22 | Outdoor low pressure sensor error | Pressure transducer fault | Check/replace low pressure sensor |
| 23 | Outdoor discharge gas thermistor error | Discharge temperature sensor fault | Check/replace discharge thermistor |
| 24 | Outdoor heat exchanger thermistor error | Condenser thermistor fault | Check/replace condenser thermistor |
| 25 | Outdoor suction gas thermistor error | Suction temperature sensor fault | Check/replace suction thermistor |
| 29 | Outdoor air thermistor error | Ambient temperature sensor fault | Check/replace outdoor air thermistor |
| 31 | Capacity setting mismatch | Indoor/outdoor capacity code incorrect | Verify capacity code settings match |
| 35 | Indoor unit number duplicated | Multiple units with same address | Assign unique addresses to each unit |
| 36 | Incompatible unit combination | Mismatched indoor/outdoor units | Verify unit compatibility |
| 39 | Constant compressor overcurrent | Running current abnormal | Check compressor, current sensor, power supply |
| 43 | Low pressure protection | Low suction pressure | Check refrigerant charge, filter, expansion valve |
| 44 | High pressure protection (repeat) | Repeated high pressure trips | Check condenser, refrigerant charge, ambient conditions |
| 45 | Discharge temperature protection | Compressor discharge overheat | Check superheat, refrigerant charge, airflow |
| 46 | Inverter compressor overcurrent | Inverter compressor drawing excess current | Check compressor, voltage, refrigerant |
| 47 | Valve locking protection | Service valve closed or restricted | Open service valves, check for restriction |
| 48 | Electrical overload | System drawing excessive power | Check power supply, reduce load |
| 53 | Inverter PCB failure | Inverter board malfunction | Replace inverter PCB |
| 54 | Inverter overheating | IPM module overheat | Check ventilation around outdoor unit |
| 55 | Fan motor error | Outdoor fan motor failure | Check fan motor, replace if necessary |
| E0 | Water pump error | Condensate pump failure | Check drain pump operation |
| E1 | Compressor thermal protection | Compressor internal protection | Check refrigerant charge, superheat |
| E3 | High pressure protection | High discharge pressure | Check condenser, fan, refrigerant |
| E5 | Inverter compressor error | Compressor startup failure | Check compressor, inverter, wiring |
| E9 | Indoor fan motor error | Indoor fan locked rotor | Check fan motor, obstructions |
| EE | Compressor protection alarm | Repeated compressor trips (3x in 6 hours) | Professional service required, check compressor |
Mitsubishi Heavy Industries
Japan • 32 error codes
| Code | Description | Cause | Action |
|---|---|---|---|
| E01 | Remote controller communication error | Wired remote controller wiring failure | Check remote controller wiring connections |
| E02 | Duplicate indoor unit address | Multiple units have same address | Assign unique address to each indoor unit |
| E03 | Indoor/outdoor communication error | Communication not established | Check wiring between indoor and outdoor units |
| E05 | Indoor/outdoor transmission abnormal | Serial communication failure | Check communication line polarity and connections |
| E06 | Indoor heat exchanger thermistor error | Evaporator sensor fault | Check/replace evaporator thermistor |
| E07 | Indoor return air thermistor error | Room temperature sensor fault | Check/replace return air thermistor |
| E08 | Heating overload protection | Overheat during heating mode | Check airflow, thermistor operation |
| E09 | Drain float switch activated | Condensate drain blocked | Clean drain line, check float switch |
| E10 | Too many indoor units connected | Over 17 indoor units on system | Reduce number of connected units |
| E16 | Indoor fan motor error | Fan motor failure or locked rotor | Check fan motor, capacitor, wiring |
| E28 | Remote controller thermistor error | Remote controller sensor fault | Replace remote controller |
| E32 | Phase wiring open or reversed | 3-phase connection error | Check phase wiring, correct phase sequence |
| E33 | Inverter current abnormal | Compressor current out of range | Check compressor, inverter board |
| E34 | L3-phase wiring open | Missing phase connection | Check 3-phase power supply connections |
| E35 | Heat exchanger temperature high | Condenser overheat | Clean condenser, check fan operation |
| E36 | Discharge temperature abnormal | Compressor discharge overheat | Check superheat, refrigerant charge |
| E37 | Outdoor heat exchanger thermistor error | Condenser thermistor fault | Check/replace condenser thermistor |
| E38 | Outdoor air thermistor error | Ambient temperature sensor fault | Check/replace outdoor air thermistor |
| E39 | Discharge pipe thermistor error | Discharge temperature sensor fault | Check/replace discharge thermistor |
| E40 | High pressure protection | High pressure switch activated | Check condenser, fan, refrigerant charge |
| E42 | Compressor overcurrent | Compressor drawing excess current | Check compressor, power supply, refrigerant |
| E43 | Low pressure protection | Low pressure switch activated | Check refrigerant charge, filter, expansion valve |
| E47 | Inverter overvoltage | DC bus voltage too high | Check power supply voltage, inverter board |
| E48 | DC fan motor abnormal | Outdoor DC fan motor fault | Check fan motor, hall sensor, wiring |
| E52 | Control circuit abnormal | Outdoor PCB fault | Check/replace outdoor control board |
| E56 | Power transistor thermistor error | IPM temperature sensor fault | Check IPM thermistor, replace if needed |
| E57 | Insufficient refrigerant | Low refrigerant charge detected | Check for leaks, recharge system |
| E59 | Compressor startup error | Compressor failed to start | Check compressor, inverter, wiring |
| E60 | Compressor position detection error | Rotor position sensor fault | Check compressor, inverter board |
| E63 | Emergency stop activated | Emergency stop input received | Check emergency stop circuit, reset |
| E64 | High pressure protection (sensor) | High pressure transducer trip | Check condenser, refrigerant, ambient |
| E68 | Current sensor abnormal | CT sensor fault | Check current transformer sensor |
Browse by Brand
Troubleshooting Tips
- • Record the exact error code - Some brands use letters, numbers, or both
- • Check for multiple errors - Some systems store error history in service mode
- • Note when the error occurs - Startup, during operation, or after running
- • Check both indoor and outdoor units - Errors may be displayed on either unit
- • Reset after repair - Clear error codes after fixing the issue
- • Some codes are informational - Not all codes indicate a fault (e.g., defrost mode)