Indoor unit displays P4; unit may not start or may shut down intermittently.

Safety Warning

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 airflow around outdoor control box, Failed inverter cooling fan (if equipped), Poor thermal contact between IPM and heatsink, High ambient temperature and heavy load

How to Fix / Troubleshooting

Safety: Turn off power before opening the outdoor unit.

1. Ensure ventilation: Clear any obstructions around the outdoor unit and control box vents.
2. Clean dust: Gently blow or brush dust off the heatsink and electronic components (avoid static damage).
3. Check small PCB fan (if present): Some models have a small fan cooling the PCB. Ensure it spins freely and runs when the unit operates.
4. If P4 persists: The inverter module may be overheating internally and require PCB replacement by a technician.

Repair Difficulty

Professional Required 5/5

Required Part

Outdoor Main PCB

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