LG Heat Pump Error Code CH25

CH25 indicates that the input supply voltage to the LG heat pump is outside the acceptable operating range. For single-phase units the required supply is 230V plus or minus 10%, and for three-phase units it is 400V plus or minus 10%. The system shuts down automatically to protect the compressor and inverter components from voltage-related damage. A technician should measure actual line voltage at the unit's terminal block to confirm the supply condition.

No. The CH25 code causes the unit to shut down intentionally, and you should not attempt to bypass or repeatedly reset the unit while the underlying voltage issue remains. Operating the heat pump on out-of-range voltage risks damaging the inverter drive board, compressor motor windings, and capacitors, which are expensive components to replace. Leave the unit off until the power supply has been inspected and corrected.

Costs vary widely depending on the root cause. If the fix is simply tightening loose connections, labor charges alone may apply, typically in the range of $75 to $200 for a service call. If new supply wiring or an upgraded disconnect is required, electrical work can range from $200 to $800 or more depending on the run length and local labor rates. A control board replacement, if needed, typically adds $300 to $700 in parts and labor on top of diagnostic costs.

Checking the voltage at the unit's terminal block requires working near live electrical terminals, which carries serious shock risk and should only be done by a qualified technician or licensed electrician. If the fault is caused by a loose connection or undersized wiring, those repairs should also be handled by a professional. Homeowners should not attempt to open the electrical compartment of the unit to diagnose this fault.

A reset may temporarily clear the fault code, but if the supply voltage is still out of range, the unit will detect the condition again and lock out with CH25 shortly after restarting. Clearing the code without correcting the voltage problem does not fix the underlying issue and risks repeated stress on internal components. The fault must be resolved at the power supply level first.