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Error code reference

Mitsubishi Air Conditioner Error Code FN2

Internal fan alarm (IP55 compatible models only)

Mitsubishi codesMitsubishi air conditioner codes

Internal fan alarm (IP55 compatible models only) - internal air circulation fan stopped due to fault or low rotation speed.

First step from the service manual

Check the internal air circulation fan for a failure.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What FN2 means on a Mitsubishi air conditioner

The FN2 error code on Mitsubishi IP55-compatible air conditioner models indicates an internal air circulation fan alarm. This fault is triggered when the indoor unit's internal circulation fan either stops completely or drops below an acceptable rotation speed threshold. The control board monitors fan motor feedback, typically through a Hall effect sensor or tachometer signal, and raises this alarm when the actual speed deviates significantly from the commanded speed or ceases entirely.

The internal air circulation fan is responsible for moving air across the evaporator coil and distributing conditioned air into the space. On IP55-rated models, which are designed for environments with higher exposure to dust and water ingress, this fan assembly is subject to additional mechanical stress and environmental contamination compared to standard indoor units. When the fan fails to reach or maintain proper RPM, the unit shuts down to prevent overheating of internal components and to avoid damage to the compressor caused by inadequate heat exchange.

Common root causes include a seized or failing fan motor, a faulty motor capacitor, degraded wiring or connector faults between the motor and control board, and debris or contamination obstructing the fan blade. In some cases, the motor itself may be electrically functional but the feedback signal circuit has failed, causing the board to incorrectly register a fan stoppage. Diagnosis should begin with a physical inspection of the fan for free rotation, followed by checking the motor's electrical supply and feedback signal continuity.

Source: manufacturer service documentation.

Common causes of FN2

  1. 01

    Seized or failed fan motor

    Part replacement

    The fan motor bearings can wear out or seize, preventing the blades from spinning. You may notice unusual noise before failure, or the motor may be completely locked and will not turn by hand.

  2. 02

    Fan blade obstruction or debris

    Wiring / connection

    Accumulated dust, debris, or a foreign object can block the fan blade from rotating freely, especially in the dusty or humid environments that IP55 models are often installed in. Inspect the fan assembly for anything physically blocking rotation.

  3. 03

    Faulty motor run capacitor

    Part replacement

    A degraded or failed run capacitor can prevent the fan motor from starting or cause it to run at insufficient speed. The capacitor should be tested for correct capacitance and replaced if it is out of specification.

  4. 04

    Wiring or connector fault between motor and control board

    Wiring / connection

    Loose, corroded, or damaged wiring connections can interrupt power supply to the motor or disrupt the tachometer feedback signal, causing the board to register a fan fault even if the motor is physically intact. Inspect all connectors and wiring harnesses in the fan circuit.

  5. 05

    Defective control board

    Part replacement

    If the motor and wiring check out correctly, the indoor unit control board may have failed and is either not sending the proper drive signal to the motor or is misreading the feedback signal. This is a less common cause and should be diagnosed only after ruling out the motor and wiring.

See the test procedure for each cause

Frequently asked questions about FN2

What does FN2 mean on a Mitsubishi air_conditioner?
FN2 is an internal fan alarm that appears on Mitsubishi IP55-compatible air conditioner models. It indicates that the indoor air circulation fan has stopped or is rotating at a speed below the acceptable minimum. The unit shuts down automatically when this fault is detected to protect internal components from heat damage.
Can I fix the FN2 error myself, or do I need a technician?
A homeowner can safely check whether the fan blade is physically obstructed by debris or dust, which is a simple visual inspection. However, testing the motor, capacitor, wiring continuity, and control board signals requires electrical knowledge and appropriate test equipment, so a qualified technician is recommended for anything beyond a basic visual check.
Is it safe to keep running my Mitsubishi air conditioner when FN2 is displayed?
No. When the FN2 fault is active, the unit has already shut down to prevent damage. Attempting to override or repeatedly restart the system without resolving the underlying fan fault can cause the evaporator to ice over, lead to compressor damage from poor heat exchange, or cause electrical components to overheat. The fault should be diagnosed and repaired before resuming normal operation.
Will resetting the unit clear the FN2 error code?
A power reset may temporarily clear the fault display and allow the unit to restart, but if the fan motor, capacitor, or wiring has a genuine fault, the FN2 error will return once the control board detects the problem again. Resetting without repairing the root cause is not a solution and can delay proper diagnosis.
How much does it cost to repair a Mitsubishi FN2 fan fault?
Repair costs vary depending on the specific failed component. A simple debris cleaning or wiring repair is typically the least expensive outcome. Replacing a fan motor or capacitor generally falls in a moderate cost range, while a control board replacement is usually the most expensive repair. Labor costs and regional pricing will also affect the total, so obtaining a quote from a certified technician after diagnosis is the best approach.

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