Indoor unit shows F3, often associated with outdoor temperature sensing issues

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

Open or shorted outdoor ambient sensor (T4), Sensor exposed to direct sunlight or heat source, Loose connector on outdoor PCB, Damaged sensor cable

Safety first: Turn off power at the outdoor disconnect before opening the outdoor unit.

Locate sensor: The outdoor ambient sensor is usually mounted near the air intake grille of the outdoor unit.
Inspect mounting: Ensure the sensor is not touching hot surfaces and is shaded from direct sunlight as per Tosot installation guidelines.
Check connection: Reseat the sensor connector on the outdoor PCB and inspect for corrosion.
Replace sensor: If F3 remains, replace the outdoor ambient temperature sensor.

Medium 3/5

Outdoor Ambient Temperature Sensor (T4)

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