Carel AL011

What does Carel AL011 mean?

AL011 on the Carel FLSTDmSCHE screw chiller is the first custom general alarm — a user-defined input that signals a site-specific condition monitored by the pCO5 controller. The alarm text and trigger source are configured by the commissioning technician. When AL011 fires, the controller shuts down the unit and all compressors in a controlled sequence. This is a manual-reset alarm.

Symptoms

• AL011 displayed on pCO5 terminal with full unit controlled shutdown
• The display description may show a custom text label set during commissioning
• All compressors stopped; cooling output lost

Common causes

• The digital input or network variable configured as AL011's trigger has opened or signaled an alarm state
• External safety device connected to the AL011 input has operated — e.g., smoke detector, flood sensor, or remote interlock
• Wiring fault on the AL011 digital input causing a false open-circuit trigger
• Commissioning error — wrong input or inverted polarity assigned to AL011

Diagnostic steps

1. 01

   Identify the AL011 trigger source

   Check the chiller commissioning records or the pCO5 configuration to identify which digital input or network variable is assigned to AL011 and what external device it monitors.

2. 02

   Inspect the triggering device

   Go to the physical location of the device connected to the AL011 input. Check whether the device has actually operated (e.g., a water detector sensing moisture, an interlock contact open) or if the wiring has failed.

3. 03

   Check wiring continuity on the AL011 input

   With the controller powered down, measure continuity on the AL011 digital input cable. An open circuit where a closed contact is expected confirms a wiring break rather than a genuine safety event.

4. 04

   Resolve the triggering condition

   If a genuine safety event occurred (e.g., flooding, fire), resolve the hazard before resetting the alarm. If the trigger was a wiring fault, repair the cable and re-terminate the input.

5. 05

   Manually reset AL011

   Press the ALARM button on the pCO5 terminal to reset AL011 after the cause is resolved. The unit will restart and begin loading compressors according to the normal control sequence.

When to call a professional

If AL011 is connected to a safety device (fire, gas, or flood detection system), do not reset the alarm until the safety hazard is evaluated and cleared by the appropriate professional. For wiring faults that are difficult to trace in multi-conductor control cables, a licensed electrician or controls technician should perform the diagnosis.