Compressor overcurrent interruption

What does UP mean?

Compressor overcurrent is detected after 30 seconds of compressor operation, indicating an excessive current draw. Potential causes include a closed stop valve, insufficient power supply voltage, incorrect compressor wiring, fan malfunctions, short cycling, or a defective compressor or outdoor controller board input circuit. This fault protects the compressor from immediate damage but requires prompt resolution to prevent component failure.

• Refrigerant overcharge or non-condensable gases causing excessively high discharge pressure and compressor workload.
• Insufficient heat transfer at the condenser (e.g., blocked fins, fan failure) leading to high head pressure and increased current draw.
• Contamination or degradation of the compressor lubricating oil, increasing internal friction and motor load.
• Faulty internal motor windings (e.g., winding short-to-ground, inter-turn short) leading to excessive current draw.
• Unbalanced supply voltage phases (e.g., >2% deviation) causing stress and increased current in one or more compressor windings.

Click steps to track your progress.

1. 1

   Connect a manifold gauge set to monitor suction and discharge pressures, verifying they are within operating limits.

2. 2

   Measure the current draw on each phase of the compressor motor (e.g., L1, L2, L3) using a clamp-on ammeter and compare to nameplate RLA.

3. 3

   Verify the supply voltage at the compressor terminals (e.g., T1, T2, T3) for phase balance and nominal voltage levels.

4. 4

   Inspect the condenser coils for cleanliness and confirm the outdoor fan is operating effectively to reject heat.

5. 5

   Perform an oil analysis (if accessible) to check for contaminants or degradation in the compressor lubricating oil.