Daikin SkyAir Error Code F6

Full Diagnosis

F6 indicates abnormally high refrigerant pressure or an overcharged system, distinguished from E3 (mechanical high-pressure switch trip) in that F6 is derived from thermistor readings across the refrigerant circuit rather than a dedicated pressure switch actuation. The outdoor unit reduces or shuts down compressor operation to prevent overpressure damage. A common root cause is refrigerant overcharge from an improper service fill, though a disconnected sensing thermistor can produce a false high-pressure reading with the same symptom.

All Recorded Causes

Refrigerant system overcharged beyond rated capacity, disconnected or open-circuit heat exchanger deicer thermistor, disconnected or open-circuit outdoor air thermistor, disconnected or open-circuit liquid pipe temperature thermistor, restricted or undersized outdoor coil airflow, defective outdoor unit control PCB.

Verify Before Replacing Parts

1. Confirm the exact Daikin model family and skyair context before acting on a generic code description.
2. Verify airflow first, then confirm operating pressures and temperature relationship before adjusting charge, since refrigerant system overcharged beyond rated capacity, disconnected or open-circuit heat ex….
3. Look for restrictions, iced coils, or dirty heat-transfer surfaces that can mimic a charge problem, and separately confirm the next candidate on the list.
4. After the correction, run the system long enough to confirm the skyair fault does not return under normal load.