LG Air Conditioner Error Code CH25

CH25 is a power supply fault indicating that the LG air conditioner has detected a voltage level outside its safe operating range, either too low or too high. The unit shuts down automatically to protect the compressor, inverter board, and other internal electronics from damage. The fault is monitored continuously by the control board and logged whenever voltage deviates from acceptable limits.

No, you should not attempt to bypass or ignore the CH25 fault. The unit has shut down specifically to prevent damage from abnormal voltage, and running the system under these conditions risks burning out the compressor or inverter board, which are significantly more expensive to replace. Leave the unit off until the voltage supply issue has been diagnosed and corrected.

Repair costs depend on the root cause. If the issue is a loose connection or a circuit breaker that needs replacement, costs are typically in the range of $75 to $250 including a service call. If the power supply board or inverter PCB inside the unit requires replacement, parts and labor can range from $300 to $700 or more depending on the model and local labor rates.

Some causes of CH25, such as a tripped breaker or a loose disconnect connection, can be addressed by a knowledgeable homeowner, but working with electrical panels and high-voltage wiring carries serious safety risks. Measuring supply voltage at the unit's terminal block requires a multimeter and comfort working around live circuits. If the issue involves internal components like the power supply board or inverter PCB, a licensed technician should perform the repair.

A reset by powering the unit off at the breaker for several minutes may temporarily clear the fault code, but if the underlying voltage problem persists, CH25 will return once the unit restarts and detects the condition again. A reset is useful for confirming whether the fault was caused by a transient event like a brief utility fluctuation, but it does not address a chronic wiring or supply problem.