Compressor overcurrent interruption (Locked rotor)

What does UF mean?

Compressor overcurrent is detected within 30 seconds of starting, indicating a locked rotor condition. This can be caused by a closed stop valve, low power supply voltage, incorrect compressor wiring, or a defective compressor or outdoor power board. This fault causes an immediate shutdown to prevent damage, but recurring issues can severely shorten compressor lifespan.

Additional Steps

Steps 1–2 are listed in Priority Fix.

1. 3

   Inspect compressor wiring (U·V·W phase) for looseness, disconnection, or incorrect polarity. Refer to Section 10-9.

2. 4

   Test the compressor for proper operation and resistance values. Refer to Section 10-6.

3. 5

   Replace the outdoor power circuit board if all other components are verified to be functioning correctly.