Bitzer Screw Compressor CSH/CSN Error Code AL11

Bitzer Refrigeration Critical Safety

Model: Screw Compressor CSH/CSN | Code: AL11

Applicable Systems
Octagon 4-Comp

Symptoms

The compressor reports that the safety valve has opened. The system pressure exceeded the safety valve setpoint and the valve has relieved pressure.

Possible Causes

  • Excessive system pressure from condenser failure
  • Safety valve setpoint drifted below normal operating pressure
  • Safety valve seat damaged causing premature opening

Troubleshooting Steps

  1. Step 1: Investigate the cause of excessive pressure and correct it
    System pressure returns to normal range
  2. Step 2: Verify the safety valve setpoint against the specification
    Valve setpoint matches the design pressure
  3. Step 3: Replace the safety valve if it does not reseat properly
    New valve seals and holds pressure correctly

How to Reset

To reset: Resolve the overpressure condition, replace or reseat the safety valve, then reset the alarm.

Source: Bitzer Screw Compressor Operating Instructions, Bitzer Kuhlmaschinenbau GmbH

Category: Refrigeration