Carel AL260

What does Carel AL260 mean?

AL260 is a High Pressure alarm 1 on the Carel µChiller system. The refrigerant high-pressure switch or pressure transducer on circuit 1 has detected that discharge pressure has exceeded the safety limit. The controller shuts down circuit 1 compressors immediately to prevent damage to the compressor, condenser, and refrigerant piping.

Symptoms

• Circuit 1 compressors shut down immediately on alarm activation.
• AL260 displayed on controller with buzzer and Alarm LED active.
• Discharge pressure above the high-pressure switch trip point.
• Manual reset required to restart the circuit in most configurations.

Common causes

• Condenser coils fouled with dirt, scale, or debris reducing heat rejection.
• Condenser fan failed or running at reduced speed.
• Refrigerant overcharge increasing condensing pressure.
• Non-condensable gases (air) trapped in the refrigerant circuit.
• High ambient temperature pushing condensing pressure above the pressure switch set point.

Diagnostic steps

1. 01

   Identify and eliminate the high-pressure condition before reset

   Do not reset the alarm while the condition persists. Allow the system to equalize and identify the root cause before re-energizing compressors.

2. 02

   Inspect and clean the condenser

   Check condenser coils or cooling tower for fouling. Clean air-cooled coils by blowing out debris or washing, depending on the condenser type. Fouled condensers are the most common high-pressure cause.

3. 03

   Verify condenser fan operation

   Confirm all condenser fans are running at rated speed with correct rotation. A failed or reversed fan significantly reduces heat rejection and raises head pressure.

4. 04

   Check for non-condensables

   Connect service gauges to the high-side. If discharge pressure is abnormally high relative to the ambient saturation temperature for the refrigerant, non-condensable gas contamination is likely. Recover refrigerant, evacuate, and recharge.

5. 05

   Manually reset the alarm and monitor

   After correcting the root cause, manually reset AL260 on the controller. Monitor discharge pressure for 15 minutes after restart to confirm stable operation below the alarm threshold.

When to call a professional

A licensed technician is required for refrigerant recovery, non-condensable purging, and recharge. If the high-pressure alarm trips repeatedly despite a clean condenser and properly operating fans, a refrigerant charge assessment, pressure switch calibration check, or compressor valve inspection is needed — all of which require specialized refrigeration tools and certifications.