LG Heat Pump Error Code P9

P9 on an LG heat pump means the compressor has shut down because the refrigerant pressure dropped below the low pressure protection threshold. In cooling mode, the trigger point is below 3 kg/cm²G, and in heating mode it is below 1.5 kg/cm²G before pump down begins. The system shuts the compressor off automatically to prevent internal damage from running with insufficient refrigerant pressure.

No. The P9 code means the system has already shut the compressor down as a protective measure. Attempting to bypass or repeatedly reset the unit without addressing the underlying cause risks permanent compressor damage, which is one of the most expensive components in the system. Leave the unit off until the root cause has been diagnosed and corrected.

Repair costs vary significantly depending on the root cause. Diagnosing and recharging a refrigerant leak after repair typically ranges from a few hundred dollars to over one thousand dollars depending on leak location and refrigerant type. An EEV replacement can range from a few hundred to several hundred dollars in parts and labor. A failed compressor, which P9 is designed to prevent, is the most expensive outcome and can range from several hundred to well over one thousand dollars depending on the unit.

Some basic checks are accessible without special tools, such as inspecting and cleaning air filters, confirming the indoor unit fan is spinning, and checking that all supply and return vents are unobstructed. However, diagnosing EEV operation, checking actual refrigerant pressures with manifold gauges, and handling refrigerant all require certified HVAC technician tools and licensing. Attempting refrigerant work without proper equipment can be dangerous and is illegal in many jurisdictions.

A power reset may temporarily clear the P9 code and allow the unit to restart, but the fault will return quickly if the underlying problem is not resolved. If refrigerant pressure is still below the protection threshold when the compressor attempts to start again, the system will shut down and display P9 again. Resetting without repair is not a solution and increases the risk of compressor damage.