LG Therma V fault 40

What it means

Comp control is not possible due to CT sensor error in Inv Driver.

Likely causes

1. CT sensor error in Inverter Driver
2. Insufficient power-on time before operation (less than 12 hours)
3. Faulty IPM (Intelligent Power Module)
4. Faulty compressor (insulation or coil failure)
5. Faulty inverter board
6. Unstable or zero output voltage from inverter
7. Fan locked
8. Obstruction/shield around the heat exchanger
9. Insufficient distance between product and wall
10. Piping condition issues such as pipe bending
11. EEV operation/connection status fault
12. Abnormal refrigerant pressure
13. Compressor restraint
14. Compressor wiring reverse phase loss
15. Short circuit or opening of internal connection line in compressor
16. Compressor winding resistance out of spec
17. Compressor insulation resistance failure
18. Inverter PCB assembly or connector connection fault
19. IGBTM failure

Where to start

1. Step 1: Check how long power has been on during operation. If power on for 12 hours or more, go to No.2. If power on for 12 hours or less, apply power for the designated time (12 hours) then go to No.2.
2. Step 2: Check if failure appears again when starting operation.
3. Step 2a: If the compressor stops and the same error appears again, check if IPM may have failed.