How to Fix / Troubleshooting

Safety first: Power off at the disconnect. Refrigerant circuit work requires certified technicians.

Steps:

Check coil cleanliness: Clean outdoor and indoor coils to ensure proper heat exchange.
Listen for valve operation: During mode change (cooling to heating), listen for the click of the four-way valve. No sound may indicate a stuck or non-energized valve.
Check coil temperatures: A technician can compare suction and discharge line temperatures to verify correct valve operation.
Sensor and charge check: A technician should verify discharge pressure sensor readings and system charge, then replace the sensor or adjust charge as needed.
Replace four-way valve: If the valve is confirmed stuck or leaking internally, it must be replaced by a technician with proper brazing and evacuation procedures.

System stops with P8, may occur during defrost or mode change

Possible Causes