LG air conditioner CH05: the indoor–outdoor communication line
The indoor unit powers up and the fan runs, but nothing gets cold and CH05 (or CH53) appears on the display or flashes on the indicator LEDs.
Solutions
Air conditioners
1 procedures · 16 codesSplit, multi-split and Artcool. CH codes, sensors and inverter boards.
Error codes
Air conditioners
Showing 16 / 16 codes
| Code | Meaning | First check | Procedure |
|---|---|---|---|
| CH01AC | MeaningIndoor room-temperature sensor is open or shorted.Service call likely | First checkSensor clip behind the front grille; it pops out during filter cleaning and gets left loose. | · |
| CH02AC | MeaningIndoor pipe inlet sensor fault.Service call likely | First checkThe sensor bulb should be clipped tight to the copper, not dangling in air. | · |
| CH04AC | MeaningDrain pump / float switch tripped: condensate is not leaving the indoor unit.User-fixable | First checkBlow through the condensate line outdoors; biofilm blocks it every couple of seasons. | · |
| CH05AC | MeaningCommunication error between indoor and outdoor units.Service call likely | First checkInterconnect terminal block at the outdoor unit, loose or corroded wire 3 is the classic cause. | Open guide |
| CH06AC | MeaningIndoor pipe outlet sensor fault.Service call likely | First checkCompare both pipe sensors cold: matching resistance rules the pair out. | · |
| CH09AC | MeaningIndoor unit EEPROM error.Service call likely | First checkPower-cycle at the isolator for two minutes. Persisting means the indoor PCB needs replacing. | · |
| CH10AC | MeaningIndoor BLDC fan motor locked.Service call likely | First checkSpin the barrel fan by hand: dust cake on the blades adds enough drag to trip this. | · |
| CH21AC | MeaningOutdoor IPM fault: inverter power module overcurrent.Service call likely | First checkClear the condenser coil and confirm the outdoor fan spins freely before any board work. | · |
| CH22AC | MeaningOutdoor high current (CT2): the compressor is drawing too much.Service call likely | First checkRestricted airflow or overcharge. Check the coil, the fan and the ambient temperature first. | · |
| CH23AC | MeaningDC link low voltage at the outdoor inverter.Service call likely | First checkSupply voltage under load at the outdoor terminal, long thin runs sag here. | · |
| CH26AC | MeaningDC compressor position error: the compressor will not start.Service call likely | First checkCompressor winding resistance and the three-phase plug seating at the inverter. | · |
| CH32AC | MeaningDischarge pipe temperature too high.Service call likely | First checkUsually undercharge or a restriction. Do not top up refrigerant without finding the leak. | · |
| CH41AC | MeaningCompressor discharge temperature sensor fault.Service call likely | First checkSensor pocket on the discharge line: heat cycling works the clip loose. | · |
| CH44AC | MeaningOutdoor air temperature sensor fault.Service call likely | First checkSensor sits behind the outdoor grille; insects nest around it and crush the lead. | · |
| CH53AC | MeaningCommunication error, indoor unit to outdoor unit signal line.Service call likely | First checkInterconnect cable run: staples through the sheath and shared conduit with mains both cause this. | Open guide |
| CH60AC | MeaningOutdoor unit EEPROM error.Service call likely | First checkIsolate for five minutes. If it returns, the outdoor PCB has lost its calibration data. | · |
No code matches that search.
Codes vary by model year and platform. Always confirm against the manual for your exact model number before ordering parts.