F3
Fujitsu
Discharge Temperature High Protection
Indoor unit shows F3, unit may shut down during extreme temperatures
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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, Low indoor airflow due to dirty filters or coil, Refrigerant undercharge or overcharge, Faulty discharge pipe thermistor
How to Fix / Troubleshooting
Safety first: Turn off power before cleaning or opening panels. High compressor discharge temperatures can damage the system.
- Clean filters and coils:
- Wash indoor air filters and ensure they are fully dry before reinstalling.
- Inspect and clean indoor coil if heavily dust-laden.
- Clean outdoor coil as described in F1.
- Check indoor airflow: Ensure supply registers are open and not blocked by furniture or curtains.
- Sensor check: A technician should verify discharge thermistor readings and replace the sensor if it is misreading.
- Refrigerant diagnosis: If airflow is good and F3 persists, a technician must check refrigerant charge and system pressures.
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Repair Difficulty
Hard
4/5
Required Part
Discharge Pipe Thermistor
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