LG Air Conditioner Error Code CH05

CH05 indicates a communication error between the indoor PCB and the outdoor PCB. The two control boards exchange continuous data signals to coordinate system operation, and CH05 appears when that signal link is lost or degraded. The system will typically shut down and display this code until the communication fault is resolved.

No. When CH05 is active, the indoor and outdoor units cannot coordinate safely, and the system will typically lock out operation on its own. Attempting to force the unit to run without resolving the communication fault risks improper compressor operation and potential damage to system components. The unit should remain off until the fault is diagnosed and repaired.

Resetting the unit by cycling power may temporarily clear the CH05 code, but if the underlying communication fault is still present, the error will return once the system attempts to operate. A reset is useful for confirming whether the fault is intermittent, but it does not resolve the root cause. The wiring and boards must be inspected to achieve a lasting repair.

Some CH05 causes, such as a loose or disconnected wire at an accessible terminal block, can be addressed by a confident DIYer with basic electrical knowledge. However, diagnosing whether the fault lies in the wiring, the outdoor PCB, or the indoor PCB requires voltage testing and component-level inspection that is best handled by a trained technician. Working near the outdoor unit also involves exposure to line voltage, so caution is essential.

Repair costs vary widely depending on the root cause. A simple wiring fix or terminal cleaning might cost between $75 and $150 in labor. If an indoor or outdoor PCB needs replacement, parts alone can range from $150 to $400 or more depending on the model, with additional labor on top of that. Getting a diagnostic visit from a certified technician is the best way to get an accurate estimate.