AHT Cooling Systems E11 Error Code
Low battery voltage (see → Chapter 10.2.3) E12 Fault in software class B (safety
Source: vento-spi__aht-vento-iom.pdf
What does AHT Cooling Systems E11 mean?
The control board reports low battery voltage. The Vento control system includes an internal battery (see AHT Vento IOM Chapter 10.2.3) that maintains date and time data during power interruptions. When battery voltage falls below the minimum threshold, E11 is triggered. The AHT manual explicitly states to contact maintenance immediately when E11 appears.
Symptoms
- E11 displayed with red status LED.
- Date and time data on the controller may reset after power cycling.
- Buzzer may activate at fault onset.
- No impact on refrigeration performance — cooling continues normally.
Common causes
- Internal clock/RTC battery depleted due to age (typical service life 3–5 years).
- Battery connector loose or corroded on the control board.
- Battery discharged by extended power outage drawing on battery backup.
- Defective replacement battery installed with insufficient capacity.
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Diagnostic steps
Note the fault and contact AHT service immediately
Per the AHT Vento operating manual, E11 requires immediate contact with the maintenance service (Chapter 10.4). Record the device type and serial number.
Locate battery replacement instructions
The AHT Vento IOM Chapter 10.2.3 provides battery replacement instructions. A separate replacement instruction sheet is available to qualified staff from AHT.
Confirm battery type
Battery type is specified in the AHT battery replacement instructions. Use only the specified battery type to ensure correct voltage and capacity.
Replace the battery
Follow the AHT battery replacement procedure exactly. Incorrect removal sequence can cause loss of configuration data on the control board.
Verify date and time after replacement
After battery replacement, set the controller date and time correctly to ensure defrost schedules and data logs are accurate.
Confirm fault cleared
E11 should clear once a healthy battery is installed. If E11 persists after replacement, the battery circuit on the control board may be faulty — contact AHT service.
When to call a professional
Battery replacement on the control board should be performed by an AHT-authorized technician using the correct procedure to avoid data loss or board damage. Contact AHT at 00800/73783248 or www.aht.at/service.
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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 air intake sensor E04 Fault in air outlet sensor E05 Fault in slat sens
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
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