CH21

DC Peak (Compressor IPM Fault)

Home Appliance Error Codes LG Split AC

Can you still use it? No, unplug it

Who can fix it? Needs an authorized technician

Typical repair time 1 hour – 8 hours

Typical cost SAR 150 to 5,000

What it means

This code appears on LG inverter split air conditioners and on LG ducted and cassette units that use CH codes. It means the outdoor inverter board detected an instant current spike in the IPM that drives the compressor, and stopped the compressor at once to protect it. The cause can be the IPM itself, the compressor or severe operating conditions. The same code can mean something else on other brands.

Models covered: LG inverter split air conditioners (e.g. Dual Inverter) and LG ducted/cassette units that use CH codes; the code shows as CH plus a number on the display or as LED blinks.

Symptoms4

CH21 shows and the compressor stops right after starting or within minutes.
The unit tries to restart several times, then stops for good.
The air is not cold even though the indoor fan runs.
The fault may show in the hottest hours or after a power cut or voltage swing.

Possible causes6

Failed IPM or outdoor inverter PCB.
Loose or burnt compressor wires or connector between the board and the compressor.
Compressor fault: shorted windings or a mechanically seized compressor.
Overload on the compressor from a dirty condenser, a stopped outdoor fan or refrigerant overcharge.
Severe supply voltage swings or poor earthing.
Poor cooling of the IPM heat sink (dry thermal paste or loose screws).

How to diagnose6

Switch off the breaker for several minutes, then restart; if the code returns quickly, do not keep retrying.
Check that the outdoor unit is clean, has room for air to leave, and that its fan turns.
After the board has discharged, a technician inspects the compressor wires and connector and checks they are tight.
Measure the compressor winding resistance against LG specification and check insulation between windings and the compressor body.
Test the IPM with a meter per the service manual procedure, and check supply voltage and refrigerant pressures.
If the compressor and wiring are good, the outdoor PCB is the main suspect.

How to fix6

Clean the outdoor condenser and remove anything blocking airflow.
Repair or replace the compressor wires and connector.
Correct the refrigerant charge to the nameplate amount if overcharged (licensed technician).
Replace the outdoor PCB (or the IPM where it is sold separately).
Replace the inverter compressor if its windings are shorted or it is seized, with system flushing, vacuum and recharge.
Run the unit long enough in hot conditions, watching current draw and making sure the code does not return.

Repair cost

0–200

200–600

600–1,500

1,500+

In Saudi riyals; the highlighted part is the expected range for this fault.

The low end covers cleaning the condenser or fixing compressor wiring; most cases end with an outdoor PCB, and the top end is a new inverter compressor.

Prices are rough estimates including the part and the technician’s fee, and vary with brand, model and part source.
Prices last updated: September 2026

Frequently asked questions

Does CH21 mean the compressor is dead?

Not always. Many cases are an outdoor PCB or compressor wiring fault; the compressor is only condemned after its windings and insulation are measured.

Why not keep restarting the unit?

Each attempt pushes high current through the IPM and compressor, and repeated tries can turn a board fault into compressor damage or the other way round.

Does Saudi summer heat cause this code?

Heat alone does not break parts, but combined with a dirty condenser or a weak outdoor fan it raises the load on the compressor and IPM, making the code more likely.

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This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.

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