Carel AL27

What does Carel AL27 mean?

AL27 is the Built-in Humidifier High Current alarm on the Carel Standard Air-conditioner (030221426). The integrated steam humidifier has drawn more current than its rated limit, indicating either a scale-blocked cylinder allowing excessive conductivity between the electrodes, or an electrical fault. The humidifier disables on this alarm to prevent overloading the supply circuit.

Symptoms

• Built-in humidifier stops producing steam and is disabled.
• AL27 displayed on the controller.
• Humidifier cylinder may have visible heavy scale buildup on the electrodes.
• Circuit breaker feeding the humidifier may trip on severe overcurrent.

Common causes

• Heavy scale buildup between electrodes increasing water conductivity and current draw.
• Supply water conductivity too high for the cylinder configuration.
• Partially short-circuited cylinder from scale bridging between electrode surfaces.
• Incorrect cylinder type installed — higher-capacity cylinder drawing more current than rated.
• Electrical wiring fault causing an external current path.

Diagnostic steps

1. 01

   Inspect the humidifier cylinder for scale

   Remove the humidifier cylinder and inspect electrode surfaces for heavy scale or bridging between electrodes. Scale deposits significantly increase water conductivity, driving current above the limit.

2. 02

   Clean the cylinder and electrodes

   Follow the manufacturer descaling procedure for the cylinder type. For openable cylinders, clean electrode surfaces and the cylinder wall. For disposable cylinders, replace if heavily scaled.

3. 03

   Check supply water conductivity

   Measure the conductivity of the incoming water supply with a conductivity meter. Water conductivity above the rated range for the cylinder causes chronically high current. A water treatment or dilution system may be required.

4. 04

   Verify the correct cylinder type is installed

   Confirm the cylinder model number matches the controller configuration. An oversized cylinder for the unit's power rating draws excessive current from the start.

5. 05

   Restart and monitor current

   After cleaning or replacing the cylinder, restart the humidifier and monitor current draw for the first fill cycle. Current should be within the rated limit for the configured cylinder capacity.

When to call a professional

Contact a Carel service technician if AL27 returns immediately after cylinder replacement with correctly rated components, or if a wiring short circuit is suspected. Electrical fault investigation inside the precision air conditioning unit requires qualified electrical personnel.