Outdoor fan motor error

What does U8 mean?

The outdoor fan motor is abnormal if its rotational frequency is detected as abnormal during operation, specifically 100 rpm or below for 1 second at 30°C or more, or 30 rpm or below/1000 rpm or more for 1 minute continuously. This indicates a problem with the fan motor or its control circuit. Failing to resolve this can lead to insufficient heat exchange, compressor overheating, and overall system performance degradation.

• Seized or stiff fan motor bearings increasing friction, preventing the motor from reaching commanded speed.
• Debris (e.g., leaves, ice) obstructing the fan blade, causing mechanical impedance and reduced RPM.
• Faulty motor speed feedback sensor (e.g., Hall effect sensor, encoder) providing inaccurate or no rotational frequency data.
• Intermittent power supply to the outdoor fan motor causing irregular speed or complete stoppage.
• Damage to the fan motor's windings (e.g., inter-turn short, open phase) resulting in insufficient torque.

Click steps to track your progress.

1. 1

   Power off and manually rotate the outdoor fan blade to check for mechanical resistance or binding.

2. 2

   Using a tachometer, measure the actual rotational speed of the fan motor and compare it to the commanded speed (e.g., Parameter P2-10).

3. 3

   Verify the integrity of the fan motor's speed feedback signal at the control board's input terminals (e.g., X12-PIN3) using an oscilloscope.

4. 4

   Measure resistance across each winding phase of the fan motor (e.g., U, V, W) to detect open circuits or shorts (expected values typically 1-10 Ohms).

5. 5

   Check for correct supply voltage (e.g., 230VAC) at the outdoor fan motor terminals during operation.