Compressor Overcurrent (Locked Start-up or Operation)

What does UF mean?

The compressor drew excessive current either during startup (locked rotor during start-up) or during ongoing operation (operating locked). Both conditions indicate a severe mechanical failure or an electrical issue preventing the compressor motor from rotating freely.

• Compressor overcurrent during start-up or operation.
• Locked rotor condition.
• Motor failure or excessive winding resistance.

Click steps to track your progress.

1. 1

   Measure compressor running current on all three phases using a clamp meter — observe if it spikes before tripping.

2. 2

   Measure winding resistance of the compressor motor phases (U-V, V-W, U-W) and to ground using an ohmmeter.

3. 3

   Verify correct voltage supply to the compressor terminals during startup attempt.

4. 4

   If applicable, check the start capacitor value and Equivalent Series Resistance (ESR) using a capacitor meter.