Indoor Fan Motor Feedback Error

What does 11-time blink 2.5-second OFF mean?

This fault is indicated when the rotational frequency feedback signal from the indoor fan motor is not emitted for 12 seconds after the motor begins operation. This means the control system cannot confirm the fan's speed or operation, leading to a lack of airflow, insufficient heat exchange, and potential unit overheating. Resolution is critical for maintaining proper air circulation and system performance.

• Damaged or disconnected feedback (FG/tachometer) signal wire from the indoor fan motor to the indoor P.C. board (e.g., connector J01).
• Internal failure of the indoor fan motor's hall effect sensor or encoder that generates the feedback signal.
• Physical obstruction preventing the indoor fan motor from rotating freely, even though the motor attempts to start (e.g., debris in blower, seized bearing).
• Indoor P.C. board's input circuit for the feedback signal is damaged or faulty, preventing it from correctly interpreting the motor's speed.
• Insufficient drive voltage or current to the indoor fan motor, preventing it from reaching a speed where a stable feedback signal can be generated.

Click steps to track your progress.

1. 1

   Disconnect main power to the indoor unit. Manually rotate the indoor fan blower assembly to check for any mechanical binding or obstructions.

2. 2

   Locate the indoor fan motor and its feedback cable connection to the indoor P.C. board (e.g., J01). Disconnect and reconnect to ensure proper seating.

3. 3

   Use a multimeter to check for continuity of the feedback signal wire from the motor connector back to the P.C. board connector.

4. 4

   With the unit attempting to operate, use an oscilloscope to measure the feedback (FG) signal waveform at the indoor P.C. board connector (e.g., pin 3 of J01). Verify frequency and voltage levels against specifications.

5. 5

   Measure the voltage supplied to the indoor fan motor from the indoor P.C. board (e.g., 24VDC, 300VDC for ECM motors) to ensure adequate power for rotation.

6. 6

   If the feedback signal is absent or incorrect, and the motor rotates freely, replace the indoor fan motor assembly. If the signal is present at the connector but not processed by the board, replace the indoor P.C. board.