Indoor unit displays P4 and the compressor may not run; unit may shut down.

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Blocked outdoor control box ventilation, Failed outdoor fan causing poor cooling of inverter, High ambient temperature, Faulty IPM temperature sensor

Safety first: Turn off power before opening the outdoor unit.

Check outdoor fan: Ensure the fan is running properly to cool both the condenser and the inverter module.
Inspect control box: Make sure the outdoor control box cover is properly installed and vents are not blocked by dirt or nests.
Clean dust: Carefully blow out dust from the PCB and heat sinks using dry compressed air.
If P4 persists: The IPM or its temperature sensor may be defective. A technician should test and likely replace the outdoor inverter PCB.

Hard 4/5

Outdoor Inverter PCB

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