F2
Fujitsu
Defrost Sensor or Defrost Control Error
Indoor unit displays F2, unit may stop in heating mode
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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
Faulty outdoor coil thermistor, Defective defrost control logic on outdoor PCB, Severely iced outdoor coil due to airflow issues, Incorrect sensor placement on coil
How to Fix / Troubleshooting
Safety first: Turn off power at the outdoor disconnect before touching the outdoor unit. Ice can be sharp and heavy.
- Check for coil icing: Inspect the outdoor coil during heating. If it is completely encased in ice and not defrosting, airflow or defrost control is suspect.
- Clear obstructions: Remove snow, leaves, or covers blocking the outdoor coil or fan.
- Sensor inspection: With power off, locate the outdoor coil thermistor used for defrost. Ensure it is firmly attached to the coil and not dangling.
- Coil cleaning: Clean a dirty coil to improve heat exchange and defrost performance.
- Technician checks:
- Measure thermistor resistance and compare to spec.
- Verify defrost cycle initiation and termination via service mode.
- Replace faulty thermistor or outdoor PCB if defrost logic fails.
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Repair Difficulty
Hard
4/5
Required Part
Outdoor Coil Thermistor (Defrost Sensor)
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