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51

Error 51 — Indoor Unit Fan Motor Error

Fujitsu · Air Conditioners

What does 51 mean?

This error occurs if the indoor unit fan motor speed is less than 1/3 of the target speed for 56 seconds, or if 0 rpm is detected for 56 seconds after the motor starts. The outdoor unit shows no indication.

Common Causes

  • Fan rotation failure (fan caught, dropped off, or locked)
  • Fan motor winding open
  • Motor protection due to excessively high surrounding temperature
  • Indoor unit fan motor failure
  • Indoor unit Power Supply PCB failure

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Turn off operation and try to rotate the fan by hand to check if it's caught, dropped off, or locked. If abnormal, address the fan or bearing.

  2. 2

    Check for excessively high temperatures around the motor, which might be causing protection. If so, let the temperature come down before restarting.

  3. 3

    If the above steps don't resolve the issue, the indoor unit fan motor or the Power Supply PCB may need replacement by a technician.

Browse all codes in this manual (118)
Verified technical data. Last updated: April 2026

Related Faults

11Error 11 — Serial communication error (Indoor unit not sending signal)12Error 12 — Wired Remote Controller Communication Error18Error 18 — External communication error
Source: Fujitsu Air Conditioners
Open Manual (Page 44)Search more codes in this manual