What does F4 error mean on AUX ASW-H09B5B4/FAR3DI-C3 Air Conditioner?
- AAndrea JohnsonSep 23, 2025
If your AUX Air Conditioner displays error code F4, it indicates an exhaust sensor error. This occurs when the outdoor unit main PCB detects a short circuit or open circuit in the exhaust sensor. Check if there is any evident resistance problem in the sensor.





