Dixell/Copeland AL20 Error Code

What does Dixell/Copeland AL20 mean?

The AL20 alarm on the Dixell IC100CX iChill controller (firmware 1.8 GRU) is a general unit alarm triggered by a digital input activation. It triggers a flashing flow regulator icon on the display and activates the alarm relay. AL20 is the parameter defining the maximum number of general alarm interventions per hour (range 0–16). When the count is reached, the alarm transitions from automatic to manual reset mode.

Symptoms

• AL20 displayed on the IC100CX FW1.8 GRU with flashing flow regulator icon.
• Alarm relay activates on each AL20 event.
• After AL20 count interventions per hour, alarm requires manual reset.
• General alarm icon visible on display during active alarm.

Common causes

• External protection device repeatedly activating the general alarm digital input.
• Intermittent fault causing repeated digital input activations within the hour.
• AL20 count set too low for the application's normal transient behavior.
• AL21 activation delay (time from digital input activation to alarm) too short.

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Diagnostic steps

1. Review the alarm event frequency

   Access the alarm log on the IC100CX and review how many AL20 events occurred in the past hour. A high count over a short window indicates a recurring intermittent condition.

2. Identify and inspect the triggering digital input

   Determine which digital input is activating the general alarm. Access the digital input status screen, identify the active input, and trace to the connected field device.

3. Resolve the root cause of the field device activation

   Investigate why the field device (e.g., flow switch, thermal relay, pressure switch) is repeatedly activating. Address the underlying mechanical or process condition causing the repeated alarm.

4. Check AL20 and AL21 parameter settings

   Confirm AL20 (maximum interventions per hour) and AL21 (activation delay in seconds) are set appropriately for the installation. Increase AL20 if normal system transients are causing nuisance trips.

5. Reset the alarm manually

   If the alarm count has been reached, navigate to AlrM on the IC100CX, select AL20, and press SET to manually reset. Address the root cause first or the alarm will immediately recur.

When to call a professional

Call a licensed HVAC/R technician if the repeated alarm activations stem from a refrigerant safety device (high-pressure switch, low-pressure switch) that is cycling, or if the count threshold AL20 needs to be adjusted and you do not have the commissioning documentation to verify the correct value.