F3
Tristar
Outdoor Pipe Temperature Sensor Fault
Outdoor unit stops and F3 is displayed; may occur in heating mode on 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 outdoor suction or discharge pipe thermistor, Loose sensor clip on outdoor piping, Weather-damaged sensor wiring, Faulty outdoor PCB sensor input
How to Fix / Troubleshooting
Safety first: Turn off outdoor power and wait for all fans and compressor to stop.
Steps to try:
- Locate sensor: Look for a small sensor clipped to a refrigerant pipe near the compressor or coil.
- Check mounting and insulation: Re-secure the sensor and wrap with insulation if missing.
- Inspect cable: UV and weather can crack insulation; replace if damaged.
- Measure resistance: Compare to Tristar’s chart. Replace if readings are abnormal.
When to call a technician: If F3 persists, the outdoor PCB may require replacement.
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Repair Difficulty
Medium
3/5
Required Part
Outdoor Pipe Temperature Sensor
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