Tempstar ductless mini-split indoor unit shows F3 and unit shuts down

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.

Possible Causes

Failed outdoor coil thermistor, Damaged sensor wiring along line set, Loose connector at outdoor control board, Faulty outdoor control board

Safety first: Turn OFF power at the outdoor disconnect.

Steps:

1. Open outdoor panel: Remove the service panel on the Tempstar outdoor mini-split unit.
2. Locate coil sensor: Find the thermistor clipped to the outdoor coil tubing and trace its wires to the control board.
3. Check for damage: Inspect the sensor and wiring for physical damage or rodent chewing.
4. Reseat connector: Unplug and reconnect the sensor at the board.
5. Restore power and test: If F3 persists, the sensor or board will need replacement by a technician.

Hard 4/5

Outdoor Coil Thermistor

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