Dixell/Copeland AL33 Error Code

What does Dixell/Copeland AL33 mean?

On the Dixell IC100CX iChill controller, AL33 controls whether the condenser water flow switch alarm is suppressed when the condenser water pump is off. Set AL33 to 0 to keep the flow alarm active even when the pump is off. Set AL33 to 1 to disable the flow switch alarm when the condenser pump is not running, preventing nuisance alarms during pump shutdown periods when no water flow is expected.

Symptoms

• Condenser water flow alarm triggers immediately when condenser pump stops (if AL33 = 0 and pump-off is normal).
• No flow alarm generated when pump is off even if flow switch contacts indicate a fault (if AL33 = 1).
• System may lock out from condenser flow alarm during normal pump cycling if AL33 is not set correctly.

Common causes

• AL33 = 0 but system design uses condenser pump cycling — nuisance alarms during pump-off periods.
• AL33 = 1 but a genuine condenser flow loss occurs during pump operation — alarm is masked.
• AL31 (condenser flow switch alarm configuration: chiller only, HP only, or both modes) mismatched with AL33.

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Diagnostic steps

1. Determine condenser pump operating mode

   Review whether the condenser water pump (CO26 parameter) runs continuously or cycles. If the pump cycles off during normal operation, set AL33 = 1 to suppress flow alarms during off periods.

2. Verify AL31 configuration

   Check AL31 (0 = not used, 1 = chiller mode only, 2 = heat pump mode only, 3 = both modes). Confirm AL31 matches the operating modes where condenser flow protection is required.

3. Test the condenser flow switch

   With the condenser pump running, verify the flow switch closes and AL33 logic allows the alarm to activate if flow is lost. Confirm switch wiring integrity and proper calibration of the flow switch.

4. Check AL27 and AL28 delay parameters

   AL27 is the condenser flow alarm delay (seconds). AL28 is the maximum duration before the alarm becomes manual reset and blocks the pump. Verify these are set appropriately for the system.

5. Set AL33 correctly and test

   Set AL33 = 1 if pump cycling is normal, or AL33 = 0 if continuous pump operation is required and loss of flow must always alarm. Test by temporarily stopping the pump and confirming controller behavior.

When to call a professional

If condenser flow loss alarms are occurring during normal operation and cannot be resolved by parameter adjustment, a licensed HVAC/R technician should inspect the condenser water circuit for blockages, pump issues, or incorrect system balance. Chiller condenser water circuit commissioning is typically a specialist activity.