LG Therma V fault CH21

What it means

Result code output by the manual fault diagnostic function indicating the PCB assembly (inverter PCB) tested NG (not good/failed) during the diagnostic sequence.

Likely causes

1. Compressor clogged
2. Compressor internal break / short
3. Overload operation - Outdoor fan restraint, shielding, clogging
4. H/Sink and C/Box contact due to defective inverter connection
5. IGBTM burnout, PCB work bad
6. Inv PCB (Outdoor) reassembly issue
7. Inverter PCB assembly or connector connections not in good condition
8. IGBTM (IPM) failure
9. Fan locked
10. Obstruction/shield around the heat exchanger
11. Insufficient distance between product and wall
12. Piping condition issues such as pipe bending
13. EEV operation/connection status fault
14. Abnormal refrigerant pressure
15. Compressor restraint
16. Compressor wiring reverse phase loss
17. Short circuit or opening of internal connection line in compressor
18. Compressor winding resistance out of spec
19. Compressor insulation resistance failure
20. Inverter PCB assembly or connector connection fault
21. IGBTM failure

Where to start

1. Enter functions using LGMV (PC or Mobile)
2. Perform a diagnostic function via LGMV
3. Check inverter PCB assembly and connector connections are in good condition