AHT Cooling Systems E44

What does AHT Cooling Systems E44 mean?

The controller is receiving an external alarm signal. An external alarm input on the AHT Vento control board accepts a contact signal from external monitoring systems — such as a building management system, remote alarm panel, or refrigerant leak detector. E44 triggers when this input contact changes state, indicating an externally-sourced alarm condition relevant to the cabinet or its environment.

Symptoms

• E44 displayed with red LED and buzzer active.
• No internal cabinet fault — the trigger is from an external signal source.
• External alarm panel or BMS may show the originating alarm event.
• Refrigerant leak detector in the vicinity may have activated (especially on R-290 units).

Common causes

• External refrigerant leak detector signalling a gas concentration threshold exceedance.
• Building management system (BMS) sending an alarm contact to the cabinet.
• External temperature alarm or door monitoring contact activating.
• Wiring fault on the external alarm input terminal causing a false trigger.
• Incorrect commissioning of external alarm contact polarity or threshold.

Diagnostic steps

1. 01

   Identify the external alarm source

   Check the building management system, external alarm panel, or refrigerant leak detector to determine what triggered the external alarm signal to the cabinet.

2. 02

   Act on refrigerant leak alarm immediately

   If the external alarm is from a refrigerant leak detector — especially critical for R-290 (propane) units — follow the AHT Vento emergency procedure: contact maintenance service immediately, evacuate the area if gas concentration is above safe levels, and do not restart the cabinet until the leak is confirmed cleared.

3. 03

   Check external alarm input wiring

   Inspect the external alarm input terminal on the control board for loose wiring, short circuits, or incorrect contact connection that could cause a false alarm.

4. 04

   Verify external device operation

   Test the external alarm device (leak detector, BMS contact) to confirm it is operating correctly and has not malfunctioned.

5. 05

   Contact AHT service

   If the external alarm source cannot be identified or if a refrigerant leak is indicated, contact AHT service at 00800/73783248 or www.aht.at/service immediately.

6. 06

   Clear external alarm and verify

   Once the external alarm condition is resolved and confirmed safe, reset the external device and verify E44 clears on the cabinet display.

When to call a professional

If E44 is triggered by a refrigerant leak detector on R-290 equipment, treat as a safety emergency. Contact AHT service at 00800/73783248 or www.aht.at/service and local emergency services if gas concentration is hazardous. Do not restart the cabinet until an authorized technician confirms the leak is repaired and the area is safe.