Carel AL41 Error Code

What does Carel AL41 mean?

AL41 on Carel µChiller and pCO chiller controllers indicates an EEPROM error on EEV driver 1 (the electronic expansion valve driver for circuit 1). The EVD driver stores calibration and configuration data in its internal EEPROM memory. When this memory is corrupted or unreadable, AL41 activates and circuit 1 EEV control is disabled, preventing the driver from operating the valve in automatic superheat control mode.

Symptoms

• AL41 displayed on the Carel controller.
• Circuit 1 EEV driver is not controlling superheat; the valve may default to a fixed position.
• Refrigerant superheat on circuit 1 is unregulated.
• No automatic reset is possible; the driver requires attention.

Common causes

• EEV driver 1 EEPROM chip corrupted by a power surge or voltage spike.
• EEPROM chip at end of write-cycle life from excessive parameter changes.
• EEV driver 1 board hardware failure.
• Loss of supply power to the driver during a firmware write operation.

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Diagnostic steps

1. Power-cycle the EEV driver

   Switch off power to EVD driver 1, wait 30 seconds, then restore power. A transient fault may clear on re-initialization.

2. Check driver supply voltage

   Measure supply voltage at the EVD driver 1 terminals. Voltage spikes or low voltage during parameter saves corrupt EEPROM data.

3. Re-enter driver parameters if possible

   If the driver initializes but shows default values after the power-cycle, re-enter all EVD driver 1 parameters (refrigerant type, valve model, superheat setpoints) using the Carel configuration tool or controller interface.

4. Check firmware version compatibility

   Confirm that the EEV driver firmware version is compatible with the chiller controller software version. Mismatched versions can cause memory initialization failures.

5. Replace the EVD driver if EEPROM is permanently damaged

   If AL41 returns after parameter re-entry, the EEPROM is beyond recovery. Replace the Carel EVD driver 1 with a compatible replacement unit.

When to call a professional

EVD driver replacement and re-commissioning — including refrigerant type selection, valve model configuration, and superheat setpoint adjustment — requires a refrigeration engineer familiar with Carel EEV systems. Incorrect EVD configuration causes refrigerant liquid slugging or compressor overheating, both of which cause catastrophic compressor damage.