LG Air Conditioner CH 05 Error
What it means
CH05 (also shown as CH 05 or C5) is the most common LG air conditioner code. Per LG, it means a communication error between the indoor and outdoor units — the two units have stopped exchanging data. It's often a tripped breaker or a wiring/connection issue between the units.
The bottom line on the CH 05 error
CH05 is a communication error between the indoor and outdoor units, and most often the real cause is simply a tripped breaker or a loose connection. The catch is that once you rule out power, the fix moves inside the terminal blocks and control boards — work that should be left to a licensed HVAC technician.
The safe first move is LG's own reset: switch off both breakers, wait five minutes, then turn them back on together. If CH05 returns, stop resetting and call a technician; a wiring or board repair is still far cheaper than replacing the unit.
CH 05 snapshot
Beyond the breaker reset, this fix moves into high-voltage terminal blocks and control boards — shut off both breakers first and leave any terminal or PCB work to a licensed HVAC technician.
Our own at-a-glance triage of the CH 05 error, from the verified data on this page. See error-code rankings → · How we score →
Common causes of the CH 05 error
- Tripped breaker or interrupted power to the outdoor unit
- Loose, damaged, or miswired communication cable between indoor and outdoor units
- Power surge or brownout that desynchronized the two units
- Faulty indoor or outdoor PCB (control board) — less common
- Corroded or wet terminal block connections at the outdoor unit
Which LG air conditioners get the CH 05 error
CH05 (also shown as CH 05 or C5) appears across LG split-type air conditioners and heat pumps — wall-mounted single-zone units, multi-split systems, and LG's Multi V / system air conditioners — wherever a separate indoor unit and outdoor condenser exchange data over a communication line.
How to fix the LG Air Conditioner CH 05 error
- 1Check the outdoor unit breakerLook at your electrical panel and see if the breaker feeding the outdoor unit has tripped. If so, that's likely the cause of the lost communication.
- 2Power-cycle both units together (LG's official step)Turn off the breakers for BOTH the indoor and outdoor units, wait 5 minutes, then turn them back on at the same time. This is the reset LG recommends for CH05.
- 3Visually inspect the connection wiringWith power off, check that the cable between the indoor and outdoor units is intact and not pinched, chewed, or corroded. Do not open terminal covers if you're not comfortable — leave that to a technician.
- 4Retry and observeRestart the unit and watch whether CH05 returns immediately or after running for a while; note this for the servicer.
🧰 When to call a professional
LG states that if CH05 persists after a power cycle, service is required. A licensed HVAC technician should check the communication wiring, terminal blocks, and control boards. Any work inside the electrical terminals or sealed system must be done by a licensed professional.
LG CH 05 vs Fujitsu Operation + Timer Light Blinking vs Samsung E1: how they compare
How this code stacks up against related error codes for difficulty, urgency, and cost.
| LG CH 05 | Fujitsu Operation + Timer Light Blinking | Samsung E1 | |
|---|---|---|---|
| DIY difficulty (1–5) | 4 | 4 | 4 |
| Urgency (1–5) | 3 | 3 | 3 |
| Typical cost | $$ | $$ | $$ |
How much does it cost to fix the CH 05 error?
| DIY (reset breakers, check power to outdoor unit) | $0 |
| Professional wiring / terminal repair | $120–$400 |
| Control board (PCB) replacement, if faulty | $300–$700 |
Repair or replace?
CH05 is usually a power or wiring problem, not a dead air conditioner, so repair is almost always the right call. A tripped breaker or loose terminal is cheap to fix; a failed control board is more costly but still far below replacement. Only weigh replacing the unit if it is old and a major component (compressor or PCB) fails alongside recurring faults. Prices vary by model and region.
Common replacement parts for the CH 05 error
| Indoor–outdoor communication cable / connectors | $20–$120 | If pinched, corroded, or an open conductor; pro should verify with a meter | |
| Indoor or outdoor control board (PCB) | $150–$500 | Part only; diagnosis and replacement should be done by a licensed HVAC tech |
Prices are typical retail ranges and vary by model and supplier — always confirm the exact part number for your appliance before buying. We are not linking parts for this code on purpose: it is a job for a qualified technician, and the right fix here starts with a diagnosis, not a purchase.
LG CH 05 error — FAQ
＋ − What does CH05 mean on an LG air conditioner?
CH05 is a communication error between the indoor and outdoor units — they've stopped talking to each other, often after a power interruption or a wiring fault.
＋ − How do I clear the CH05 error on my LG AC?
Turn off the breakers for both the indoor and outdoor units, wait 5 minutes, then switch them back on together. If CH05 returns, LG says service is required.
＋ − Is CH05 serious?
It can be minor (a tripped breaker that just needs a reset) or more involved (damaged wiring or a failed control board). If a power cycle doesn't fix it, have a technician inspect it.
Sources & manufacturer references
This guide is independently written and not affiliated with LG. Always unplug appliances before servicing and follow your model's manual. Error codes and steps can vary by model — when in doubt, consult a qualified technician.