P4 means compressor overload. The published first check applies when the code shows at initial start-up: confirm the refrigerant valves are open. A valve left closed at commissioning can trip this code before the system ever runs normally. If the valves are already open, or you are not sure which valves the installer left you, do not force them. Note P4, switch the breaker off for a few minutes, and switch it back on. If P4 returns, call support with the code and your model number. Compressor and refrigerant work beyond that valve check belongs to a licensed HVAC technician.
What to do
- 1If this appears at initial startup, check that the refrigerant valves are open.
- 2Note the code, switch the unit off at the breaker for a few minutes, then switch it back on. If the code returns, call support with the code and your model number.