F0
Fujitsu
Refrigerant System Low Pressure / Undercharge Protection
Indoor unit displays F0, unit may not start or may shut down quickly
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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
Refrigerant leak in indoor or outdoor coil or flare joints, Severely undercharged system, Blocked or restricted expansion device, Faulty low-pressure sensor or transducer
How to Fix / Troubleshooting
Safety first: Refrigerant work must be performed by an EPA-certified (or local equivalent) technician. Do not attempt to open the refrigerant circuit yourself.
- Homeowner checks:
- Inspect visible flare joints at the outdoor unit for oil stains, which can indicate leaks.
- Listen for hissing sounds near line sets or indoor coil.
- Ensure indoor and outdoor coils are clean and not iced over.
- Technician procedures (summary):
- Connect gauges to verify low suction pressure.
- Perform leak detection on flare joints, coils, and line set.
- Repair leaks, evacuate, and recharge to Fujitsu-specified charge.
- Verify operation and clear F0 code.
- Sensor check: If pressures are normal but F0 persists, the low-pressure sensor or its wiring may be faulty and require replacement.
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Repair Difficulty
Professional Required
5/5
Required Part
Refrigerant Circuit (Leak Repair and Recharge)
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