Bitzer Screw Compressor CSH/CSN Error Code AL7

Bitzer Refrigeration Critical Power

Model: Screw Compressor CSH/CSN | Code: AL7

Applicable Systems
Octagon 4-Comp

Symptoms

The compressor reports a phase sequence error. The controller detected incorrect phase rotation, preventing compressor startup.

Possible Causes

  • Power supply phase rotation reversed
  • Wiring error during installation or maintenance
  • Phase loss detected during phase monitoring

Troubleshooting Steps

  1. Step 1: Check phase rotation at the compressor power supply
    Correct L1-L2-L3 rotation is confirmed
  2. Step 2: Verify all three phases have equal voltage
    Phase-to-phase voltages are balanced within 3 percent
  3. Step 3: Correct the wiring if the phase sequence is reversed
    Phase rotation tester shows correct direction

How to Reset

To reset: Correct the phase sequence and verify all phases, then cycle the controller power.

Source: Bitzer Screw Compressor Operating Instructions, Bitzer Kuhlmaschinenbau GmbH

Category: Refrigeration