AHT Cooling Systems E03 Error Code
Fault in air intake sensor E04 Fault in air outlet sensor E05 Fault in slat sens
Source: vento-spi__aht-vento-iom.pdf
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.
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Diagnostic steps
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.
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.
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.
Test sensor resistance
Disconnect the sensor and measure resistance at known ambient temperature. An open or shorted reading confirms the sensor must be replaced.
Replace the sensor
Install an AHT-approved air intake sensor, securing it in the correct position per AHT service documentation.
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.
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Other AHT Cooling Systems Error Codes
Fault in electronic expansion valve E01 Fault in suction pressure sensor E02 Fau
Fault in high-pressure sensor E07 Fault in compressor safety chain E08 Fault in
Fault in internal temperature sensor (Goods room) E10 Supply voltage too low/too
Low battery voltage (see → Chapter 10.2.3) E12 Fault in software class B (safety
Fault in EEPROM (control board defective) E32 Suction pressure too low E33 Super
Superheating too high E35 Internal temperature too high (goods room) E36 Interna
Control temperature too low E38 Control temperature too high E39 Run-time fault
Fault in internal memory E41 Heating gas temperature too high (pressure tube sen
Time-out Valve opening 100% E43 Condensation pressure too high E44 External alar
E03 E04 E05 E06 E07 Falha no sensor de temperatura do gas de succao (sensor do c
compressor Falha no sensor de temperatura do pressao) E10 E09 gas térmico (senso
E34 E35 (software de seguranca) Pressao de aspiracao demasiado baixa Sobreaqueci
Sources: www.aht.at