LG Heat Pump Error Code 25

Error code 25 means the unit has detected that its input voltage is outside the acceptable tolerance for its rated operating voltage, either too low or too high. The heat pump's PCB continuously monitors supply voltage and shuts down or alerts when it goes out of range. This protects the compressor and other components from damage caused by improper voltage. The issue can originate from the electrical supply, the wiring, or in some cases the control board itself.

No. Error code 25 indicates the unit is receiving voltage outside its rated tolerance, which can cause overheating, premature component failure, or damage to the compressor and control board. The unit should not be operated until the supply voltage issue has been diagnosed and corrected. Continued operation under abnormal voltage conditions risks costly damage to major components.

Repair costs vary depending on the root cause. If the issue is a loose connection or a failed breaker, costs may range from around $75 to $300 including a service call and parts. If the supply wiring needs to be replaced or upgraded, costs can range from $200 to $800 or more depending on run length and local labor rates. PCB replacement typically falls in the range of $300 to $700 including the part and labor. A diagnostic visit is the first step to getting an accurate estimate.

Some preliminary checks, such as verifying that the circuit breaker is fully seated and inspecting visible wiring connections for obvious damage, can be done by a careful homeowner. However, accurately measuring input voltage at the unit's terminal block under load requires a multimeter and comfort working near live electrical components, which is best left to a licensed electrician or HVAC technician. If the supply voltage checks out and the PCB needs replacement, that repair should be performed by a qualified technician.

A power reset may temporarily clear the code, but if the underlying voltage issue has not been resolved, the error will return once the unit attempts to operate again. Resetting without diagnosing the root cause is not a fix and may delay proper repair while the unit continues to experience abnormal voltage conditions. The supply voltage must be brought within specification, or the PCB replaced if it is the source of a false reading, before the error will stay cleared.