Dixell/Copeland AL11

What does Dixell/Copeland AL11 mean?

The AL11 alarm on the Dixell IC100CX iChill controller indicates that the condensing pressure or temperature has exceeded the high alarm setpoint. The controller activates a general alarm output, turns on the buzzer, and lights the alarm icon. The AL11 parameter defines the threshold — configurable from -40°C to 110°C (or equivalent pressure) — above which this alarm triggers.

Symptoms

• AL11 displayed on the IC100CX screen with alarm icon lit.
• Buzzer activates and alarm relay closes.
• Condensing pressure or temperature above the AL11 setpoint.
• Low pressure reading on Pb3 or Pb4 probe as condenser overloads.

Common causes

• Fouled or blocked condenser coil reducing heat rejection capacity.
• Condenser fan failure cutting airflow over the coil.
• High ambient temperature pushing condensing conditions above design limits.
• Refrigerant overcharge elevating head pressure.
• Non-condensable gases contaminating the refrigerant circuit.

Diagnostic steps

1. 01

   Check condensing pressure or temperature reading

   Compare the Pb3 or Pb4 probe value displayed on the IC100CX against the AL11 threshold. Connect manifold gauges to confirm the controller reading matches actual head pressure.

2. 02

   Inspect and clean the condenser

   Check the condenser coil and fans for dirt accumulation or failed motors. Clean the coil and verify all fans are spinning at correct speed before further diagnosis.

3. 03

   Verify ambient conditions

   Confirm the ambient temperature is within the chiller's rated operating range. If ambient exceeds design limits, the AL11 alarm is an expected protective response, not a fault.

4. 04

   Check refrigerant charge

   With gauges connected, evaluate subcooling. Excessive subcooling with high head pressure indicates overcharge; a certified technician should recover excess refrigerant.

5. 05

   Reset the alarm and monitor

   After correcting the root cause, go to the function menu on the IC100CX, navigate to AlrM, select AL11, and press SET to reset. Monitor the condensing reading to confirm the condition does not recur.

When to call a professional

Call a licensed HVAC/R technician if condensing pressure remains elevated after condenser cleaning and fan verification, if refrigerant charge adjustment is required (Section 608 certification mandatory), or if the chiller requires condenser fan motor replacement or refrigerant circuit diagnostics that exceed general maintenance scope.