P3
Mitsubishi Electric
Outdoor Heat Sink / Inverter Overheating
Outdoor unit stops with P3, often during high load or high ambient temperature
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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.
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Possible Causes
Blocked outdoor coil, Failed outdoor fan motor, Poor ventilation around outdoor unit, Deteriorated thermal paste or sensor on heat sink
How to Fix / Troubleshooting
Safety first: Turn off power at the disconnect before cleaning or servicing the outdoor unit.
Steps:
- Clean outdoor coil: Remove debris, leaves, and dirt from the coil fins using a soft brush and low-pressure water. Ensure fins are not bent closed.
- Check outdoor fan: Confirm the fan runs at proper speed when the unit operates. If it is slow, intermittent, or not running, test and replace the outdoor fan motor.
- Improve airflow: Ensure at least the manufacturer’s recommended clearance (typically 30–50 cm or more) around the unit. Remove obstructions and avoid enclosing the unit.
- Inspect heat sink sensor: On some models, a thermistor is attached to the inverter heat sink. Verify it is firmly attached and wiring is intact. Replace if faulty.
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Repair Difficulty
Medium
3/5
Required Part
Outdoor Fan Motor
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