Carel AL010 Error Code

What does Carel AL010 mean?

AL010 fires on the Carel FLSTDmSCHE screw chiller when the operating envelope data contains invalid or out-of-range values. The envelope defines the safe operating boundaries for compressor load steps, discharge pressure, suction pressure, and temperature combinations. Invalid envelope data prevents the controller from computing safe operating limits, so it shuts down the unit and all compressors in a controlled sequence. This is a manual-reset alarm.

Symptoms

• AL010 displayed on the pCO5 terminal with full unit shutdown in controlled compressor sequence
• All compressors stopped; no cooling output
• Alarm cannot be auto-reset — manual intervention required at the controller

Common causes

• Incorrect compressor operating envelope parameters entered during commissioning or after a firmware update
• Parameter restore or factory reset that loaded default envelope values incompatible with the installed compressor
• EEPROM corruption on the pCO5 board that scrambled stored envelope data
• Manual parameter entry error during configuration — values outside the controller's acceptable range

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Diagnostic steps

1. Access envelope data parameters

   Enter the manufacturer-level password on the pCO5 terminal and navigate to the compressor envelope configuration screens. Review all envelope parameters for values outside the compressor manufacturer's specified operating range.

2. Compare parameters against compressor documentation

   Obtain the operating envelope data from the screw compressor manufacturer's service manual. Verify that maximum discharge pressure, minimum/maximum suction pressure, and temperature limit parameters match the compressor specifications.

3. Correct invalid envelope entries

   Re-enter all envelope parameters with correct values from the compressor documentation. Save each parameter after entry and confirm it is stored before moving to the next.

4. Restore factory defaults if EEPROM is suspect

   If parameters appear correct but AL010 persists, perform a pCO5 parameter restore to factory defaults and re-commission the envelope data from scratch using the compressor documentation.

5. Reset the alarm and restart

   Press the ALARM button on the pCO5 terminal to manually reset AL010. The unit should restart and begin the compressor loading sequence. Monitor the first few load steps for normal operation.

When to call a professional

Screw compressor envelope data configuration is a factory-commissioning task that requires access to the compressor manufacturer's performance curves and the Carel application software documentation. If you do not have the original commissioning records or compressor data sheets, a Carel-authorized service technician with the correct documentation must re-commission the envelope. EEPROM failures on the pCO5 board require factory-level repair.