Dixell/Copeland AL16

What does Dixell/Copeland AL16 mean?

On the Dixell IC100CX iChill controller, AL16 sets the maximum number of low-pressure alarm events (from the analogue condenser input probe) allowed within one hour before the controller switches to manual reset mode. Once this count is reached, the unit locks out and requires a technician to perform a manual reset through the controller menu. This parallels AL02 but applies to the condenser analogue probe input rather than the digital LP switch.

Symptoms

• Low condenser pressure or temperature alarm trips multiple times within one hour.
• After reaching the AL16 count, the unit locks out and does not restart automatically.
• Alarm relay activates; general alarm icon illuminates on display.
• Manual reset via AL parameter menu is required to restore operation.

Common causes

• Refrigerant leak or low charge causing condenser pressure to repeatedly drop below AL14 setpoint.
• Rapid ambient temperature fluctuations cycling condensing conditions near the alarm threshold.
• AL14 low-pressure alarm setpoint set too close to normal operating condensing pressure.
• AL15 differential too small, causing the alarm to reset and retrigger rapidly.
• Faulty condenser probe causing erratic readings that cross AL14 frequently.

Diagnostic steps

1. 01

   Review alarm trip frequency

   Note how often the low condenser alarm is occurring over a 60-minute period. Frequent trips close to AL16 indicate that the AL14 setpoint or AL15 differential may need adjustment.

2. 02

   Measure condensing conditions

   Connect pressure gauges or use an independent thermometer to verify actual condenser operating conditions. Compare to AL14 setpoint to determine if trips are legitimate or nuisance.

3. 03

   Check probe accuracy

   Verify the condenser analogue probe is reading accurately. Replace if readings are erratic or do not match independent measurements.

4. 04

   Adjust AL14 and AL15 setpoints

   If legitimate low-ambient conditions drive condensing below AL14, lower the setpoint cautiously. Increase AL15 differential to reduce nuisance re-triggering.

5. 05

   Perform manual reset after resolving root cause

   Access the AL menu on the IC100CX and perform the manual reset procedure to clear the lockout. Ensure the root cause is resolved before resetting to prevent immediate recurrence.

When to call a professional

If condensing pressure is genuinely and repeatedly below design minimums, a licensed refrigeration technician must assess the refrigerant system and ambient operating conditions. Repeated lockouts causing production downtime also benefit from an engineer reviewing whether a head pressure control solution is appropriate.