LG HVAC Error Code 25

Error code 25 on an LG HVAC unit means the system has detected that the incoming supply voltage is outside the required operating range of 193 to 253V AC. The unit is designed to run on 208/240V AC, and anything below 193V or above 253V will trigger this fault. The system shuts down or faults out to prevent damage to the compressor and electronics. Restoring proper voltage is required to clear the error.

Yes, operating an HVAC system on out-of-range voltage poses real risks. Low voltage can cause the compressor motor to overheat and fail prematurely due to higher current draw. High voltage can damage the control board, capacitors, and other sensitive components. Addressing the voltage issue promptly protects both the equipment and the electrical system.

The repair cost depends entirely on the root cause. If the fix involves tightening loose electrical connections, cost is minimal and may only require a service call fee in the range of $75 to $150. If new wiring or a dedicated circuit is needed, electrical work can range from $200 to $800 or more depending on the complexity. If the voltage fault has already damaged internal components like the control board or compressor, repair costs can increase substantially.

Start by measuring the actual supply voltage at the unit's power terminals with a multimeter while the system is under load. If voltage is below 193V, inspect for loose connections, undersized wiring, or a weak breaker. If the utility supply itself is out of range, contact your electric utility provider. Once the voltage issue is corrected and supply is confirmed within the 193 to 253V AC range, the unit should resume normal operation.

Resetting the unit may temporarily clear the fault display, but the error will return if the underlying voltage issue has not been corrected. The control board continuously monitors incoming voltage, so any reading outside 193 to 253V AC will re-trigger the fault. A reset is only a useful step after the supply voltage has been confirmed to be within the acceptable range.