F3
Friedrich
Defrost Sensor / Outdoor Coil Sensor Error
Display shows F3, unit may shut down on defrost or heating (heat pump models)
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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
Failed defrost thermistor on outdoor coil, sensor not properly attached, damaged wiring, defective outdoor PCB
How to Fix / Troubleshooting
Safety: Turn off power at the disconnect before opening the outdoor section.
Steps to resolve F3:
- Access outdoor coil: Remove the outdoor panel to expose the condenser/heat pump coil.
- Locate defrost sensor: This thermistor is usually clipped to the outdoor coil where frost typically forms.
- Check attachment and condition: Ensure the sensor is firmly clipped and not dangling. Inspect for cracks or broken leads.
- Inspect wiring: Follow the sensor wires to the outdoor PCB, checking for chafing or rodent damage. Repair or replace as needed.
- Test sensor: Measure resistance and compare to the service chart. Replace if out of range.
- Outdoor PCB: If a new sensor does not clear F3, the outdoor control board may be faulty and require replacement.
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Repair Difficulty
Hard
4/5
Required Part
Defrost Thermistor
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