LG error code CH21
What it means
Outdoor DC compressor IPM (inverter power module) fault.
Possible causes
IPM module failure Compressor overcurrent due to mechanical or electrical stress Inadequate cooling of IPM heat-sink
Suggested fix
Measure compressor current and DC bus voltage, inspect the IPM and its heat-sink for damage or poor thermal contact; replace the inverter module or outdoor PCB once diagnostics confirm IPM failure and verify compressor health before energizing the new board.
Safety first. Isolate the power supply before inspecting any unit. Refrigerant-circuit
and electrical repairs must be carried out by a qualified, registered technician.
Other LG codes
- CH01 — Indoor air (room) temperature sensor fault.
- CH02 — Indoor pipe (coil) temperature sensor fault.
- CH03 — Drain pump or condensate removal error.
- CH05 — Communication fault between the indoor and outdoor unit.
- CH09 — Indoor unit EEPROM or memory error.
- CH10 — Indoor fan motor fault or abnormal fan operation.
- CH22 — Outdoor current transformer (CT) error.
- CH23 — Outdoor DC compressor overcurrent protection.
- CH61 — High temperature protection in outdoor unit (cooling) or indoor unit (heating).
- CH67 — Outdoor fan motor fault.