AHT Cooling Systems E03

What does AHT Cooling Systems E03 mean?

The control board detects a fault in the air intake sensor. This temperature probe monitors the temperature of air entering the refrigerated display case from the sales floor. An open-circuit, short-circuit, or out-of-range reading prevents the controller from managing evaporator airflow correctly and triggers E03.

Symptoms

• E03 fault code shown on display with red status LED.
• Buzzer sounds at fault onset.
• Air temperature control logic impaired; cabinet may not defrost correctly.
• Display shows abnormal temperature readings or dashes.

Common causes

• Air intake sensor open-circuit or short-circuit failure.
• Sensor lead or connector damaged by ice buildup or mechanical contact.
• Loose connector at the sensor or at the control board terminal block.
• Sensor displaced from its air intake mounting location.
• Control board sensor input channel failure.

Diagnostic steps

1. 01

   Move goods and log the fault

   Relocate temperature-sensitive goods to another suitable cabinet. Record the fault code and device serial number before calling service.

2. 02

   Locate the air intake sensor

   Find the air intake temperature probe mounted in the evaporator compartment or air duct at the inlet section of the Vento cabinet.

3. 03

   Check sensor mounting and wiring

   Confirm the sensor is properly seated in its holder and that its lead is routed without sharp bends or pinch points. Reseat the connector at both ends.

4. 04

   Test sensor resistance

   Disconnect the sensor and measure resistance at known ambient temperature. An open or shorted reading confirms the sensor must be replaced.

5. 05

   Replace the sensor

   Install an AHT-approved air intake sensor, securing it in the correct position per AHT service documentation.

6. 06

   Verify fault cleared

   Power up, confirm E03 is no longer displayed, and monitor for 2 hours before reloading goods.

When to call a professional

Sensor access may require removal of interior panels near the evaporator. Any exposure to the refrigerant circuit requires certified refrigeration personnel. Contact AHT service at 00800/73783248 or www.aht.at/service for an authorized technician.