LG Heat Pump Error Code P703

P703 means the compressor has been shut down by high pressure sensor protection control at stage 3. The system detected abnormally high pressure in the refrigerant circuit and stopped the compressor to prevent damage. This is a safety lockout that requires the underlying pressure issue to be resolved before the unit will operate normally again.

No, you should not attempt to bypass or ignore this error. The system has locked out the compressor as a protective measure against high refrigerant pressure, which if left unaddressed could cause compressor failure or refrigerant circuit damage. Leave the unit off until a technician has diagnosed and corrected the root cause.

Repair costs depend on the cause. A coil cleaning or airflow correction may cost anywhere from $75 to $200 for a service visit. Refrigerant adjustment, sensor replacement, or reversing valve replacement can range from $200 to $800 or more depending on parts and labor in your area. A compressor replacement, if damage has already occurred, is typically the most expensive outcome and can range from $1,000 to $2,500 or higher.

Some causes, like a dirty outdoor coil or blocked airflow, can be addressed by a homeowner. However, diagnosing refrigerant charge, sensor function, or valve issues requires specialized tools and refrigerant handling certification. It is best to contact a qualified HVAC technician for a full diagnosis if cleaning the coil does not resolve the fault.

A reset may temporarily clear the fault, but if the underlying cause of the high pressure condition has not been fixed, the error will return. Because P703 is a stage 3 protection event, it has likely occurred multiple times already. Repeated resets without repair risk compressor damage and can escalate the severity of the fault.