Mitsubishi Air Conditioner Error Code FN

The FN error code on a Mitsubishi air conditioner means the cooling fan has stopped, is running below the required rotation speed, or is operating differently than what the Pr.244 parameter setting expects. The system activates this alarm to prevent damage caused by inadequate airflow across the heat exchanger. The unit will typically stop normal operation until the fault is resolved and cleared.

No, you should not attempt to continue operating the unit while the FN error is active. Without proper fan operation, heat exchange is compromised, which can cause refrigerant pressure to reach unsafe levels and lead to compressor damage. The system is designed to shut down when this fault is detected specifically to prevent more serious and costly damage.

A power reset may temporarily clear the FN error code, but if the underlying fault with the fan motor, wiring, or parameter setting has not been corrected, the error will return as soon as the system attempts to operate the fan again. A reset is useful for confirming whether the fault is intermittent, but it should not be treated as a repair. The root cause must be identified and corrected to permanently resolve the alarm.

Some causes of the FN error, such as clearing a physical obstruction from the fan blade, can be addressed without professional help. However, diagnosing a failed motor, testing a run capacitor, or adjusting the Pr.244 parameter requires electrical knowledge and the appropriate tools. If you are not comfortable working with electrical components in HVAC equipment, a licensed technician should handle the repair.

Repair costs vary depending on the root cause. Clearing an obstruction or reseating a connector may cost only a service call fee, typically in the range of $75 to $150. Replacing a run capacitor is generally a low-cost repair, often $100 to $250 including parts and labor. A full fan motor replacement can range from $250 to $600 or more depending on the unit model and motor availability.