Error code reference

LG Air Conditioner Error Code 39

Communication error between master outside unit PFC and inverter board, or inverter compressor current detection (CT) sensor disconnection/short circuit.

SourceLG Air Conditioner Outside Unit - Service Manual: ARNU/URNU Seriesp. 82

LG codes LG air conditioner codes

Diagnostic procedure

The full 39 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

First diagnostic step

Check if PFC micom and INV micom S/W program versions match; upgrade micom program if needed, replace inverter PCB assembly if abnormality found.

SourceLG Multi-Inverter Air Conditioner - Service Manual (FM57AH)p. 60, 129

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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

5 manuals in the MyPros+ library document this code for LG air conditioner.

Models covered by the manuals that document this code

More models are covered than are listed here.

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The full 39 procedure

Where this code is documented

Models covered by the manuals that document this code

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