Tempstar ductless mini-split shows F5 and system cycles off quickly

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 ambient thermistor, Sensor exposed to direct sunlight or relocated, Broken sensor wiring, Faulty outdoor control board

Safety first: Turn OFF power at the outdoor disconnect.

Steps:

1. Locate ambient sensor: On many Tempstar mini-splits, the ambient sensor is mounted near the outdoor coil inlet or on the control box.
2. Check mounting: Ensure the sensor is properly mounted in free air, not touching hot surfaces or in direct sun.
3. Inspect wiring and connector: Look for damage and reseat the connector on the control board.
4. Restore power and test: If F5 persists, the sensor or board may need replacement by a technician.

Medium 3/5

Outdoor Ambient Thermistor

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