LG Air Conditioner Error Code CH27
A protection circuit in the inverter has cut power because the current feeding the compressor drive spiked. It is an electrical fault inside the outdoor unit, and repeated resets will not clear it.
Also shown as: 27
Applies to: Residential wall-split and multi-split systems
Common causes
- Short circuit in the inverter power stage
- Sudden current spike through the compressor
- Reactor or outdoor board fault
- Supply surge after a storm or power cut
What to check, in order
- Switch the unit off at the breaker and do not keep restarting it: this code means a protection circuit has already intervened.
- If the breaker itself has tripped, leave it off and call a technician.
- Note any recent storm or power cut when booking: it helps the technician judge whether a surge caused the fault.
Clear the code and test
- Fix what the checks above found first — a filter cleaned, an obstruction removed, the breaker restored. Clearing the code without fixing the cause only brings it back.
- Restore power at the breaker and switch the unit on with the remote.
- Run the unit in cooling or heating for ten to fifteen minutes and watch whether the code returns; some codes only appear after the compressor has run for a while.
- If the unit runs with no code, the fault is cleared. If the code returns, write down the code and whether the indoor or outdoor unit shows it before calling a technician — it speeds up the diagnosis.
When to call a professional
This code usually points to a faulty part, wiring or the control board on a LG air conditioner. Run the checks above to rule out the simple causes, then book a technician — and book one straight away if any of these apply:
- The code comes back after you have run the checks and a test cycle.
- You smell burning, see sparks or scorch marks, or the breaker trips.
- Water is leaking and you cannot stop it.
- The fix needs panels opened beyond what your manual describes, or a part tested with a meter, and you are not set up for that.
When you call, give the brand, the code CH27, your model number (on a label on the side of the indoor unit) and the checks you already ran. It shortens the visit.
Repair or replace?
This fault is in professional territory: the fix usually means a major part or board-level work, and the labour adds up. If your machine is already well into its service life, get the repair quote first, then compare it with the price of a current equivalent model before you decide. Paying a large share of a new machine's price to repair an old one is rarely the better deal; replacing a machine over one cheap fault is wasteful too.
Parts that may be involved
Outdoor control boardCompressor
Parts are model-specific. Find your model number first — usually on a label on the side of the indoor unit — and match the part to that number before ordering.
Questions people ask about CH27
What does CH27 mean on a LG air conditioner?
CH27 means: PSC fault: inverter protection circuit tripped. A protection circuit in the inverter has cut power because the current feeding the compressor drive spiked. It is an electrical fault inside the outdoor unit, and repeated resets will not clear it.
Can I fix LG CH27 myself?
Only the preliminary checks. Code CH27 usually means a part, wiring or the control board has failed, which is a technician job. Run the checks to rule out simple causes before you book.
How do I clear LG CH27?
Fix what the checks above found first — a filter cleaned, an obstruction removed, the breaker restored. Clearing the code without fixing the cause only brings it back. Restore power at the breaker and switch the unit on with the remote. Run the unit in cooling or heating for ten to fifteen minutes and watch whether the code returns; some codes only appear after the compressor has run for a while.
Sources checked
The meaning and checks for this code were checked against the sources above in November 2026. Codes vary by model and region; if your manual lists a different meaning for your exact model, follow the manual.