LG Heat Pump Error Code P3

P3 on an LG heat pump means the system has shut down because the low-side refrigerant pressure dropped below 1.2 kg/cm2G. The unit requires two detections of this condition within one hour before locking out, which helps filter out brief pressure dips. The lockout protects the compressor from running in a low-refrigerant condition that could cause serious internal damage.

No. The system is designed to shut itself down when P3 triggers precisely because operating with low refrigerant pressure can overheat and destroy the compressor. Repeatedly resetting and restarting the unit without fixing the underlying cause risks compressor failure, which is a much more costly repair. Leave the unit off until the fault is diagnosed and corrected.

Resetting the unit will clear the error code and allow the system to restart, but the P3 will return if the underlying pressure problem is not fixed. Since the lockout requires two low-pressure events within one hour, the system may run briefly before shutting down again. A reset is useful for diagnostic purposes after a repair, but it is not a solution on its own.

You can check a few things yourself: confirm both service valves on the outdoor unit are fully open and inspect your indoor air filter for blockage. However, if those checks do not resolve the issue, diagnosing refrigerant leaks, pressure testing, and recharging the system requires EPA Section 608 certification and professional equipment. Most P3 causes will need a qualified HVAC technician to complete the repair.

Repair cost depends heavily on the root cause. Cleaning a filter or opening a service valve costs very little beyond a service call fee, typically in the range of $75 to $150. Locating and repairing a refrigerant leak plus recharging the system can run from $200 to $600 or more depending on leak location and refrigerant type. A compressor replacement, if the unit was run in a damaged state, can cost $800 to $2,000 or higher.