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Error code reference
LG Air Conditioner Error Code C4
Heat sink sensor error: heat sink thermistor is open/short or heat sink temperature is over 95°C.
SourceLG Room Air Conditioner - Service Manual: AS-W Series (Exploded View)p. 52, 57
Diagnostic procedure
The full C4 procedure
Step 1 is visible so you can confirm you are on the right page. The remaining steps, the ones that tell you whether to actually replace a part, unlock with any pass.
MyPros+ · DiagnosticsStep 1 preview
1
First diagnostic step
Check if heat-sink TH is connected to CN-TH2 on outdoor PCB; measure resistance of TH (about 10kΩ at 25°C).
SourceLG Room Air Conditioner - Service Manual: AS-W Series (Exploded View)p. 52, 57
More steps, wiring diagram references, and verified part numbers
Includes expected resistance and voltage values, connector pinouts, and supersession notes for replacement parts.
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Where this code is documented
2 manuals in the MyPros+ library document this code for LG air conditioner.
Models covered by the manuals that document this code
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