AHT Cooling Systems E40 Error Code
Fault in internal memory E41 Heating gas temperature too high (pressure tube sen
Source: vento-spi__aht-vento-iom.pdf
What does AHT Cooling Systems E40 mean?
The controller detects a fault in the internal memory (separate from EEPROM E13 — this refers to the controller's RAM or working memory self-test). A RAM fault prevents the controller from reliably storing and executing operational variables, prompting E40 to trigger a protective shutdown and alert staff to a control board hardware problem.
Symptoms
- E40 displayed with red LED and buzzer.
- Controller may behave erratically before shutting down.
- Refrigeration operation stops; cabinet temperature rises.
- Power cycling does not reliably clear the fault.
Common causes
- Control board RAM chip failure due to component aging.
- Voltage transient or spike corrupting RAM contents and failing self-test.
- Control board hardware defect affecting memory bus.
- Severe electromagnetic interference disrupting memory operation.
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Diagnostic steps
Move goods immediately
Transfer all perishable goods to another cabinet at the correct temperature class without delay.
Record fault and device information
Note the fault code E40, device type, and serial number (from the nameplate and sticker per AHT IOM Fig. 13).
Attempt a single power cycle
Cycle power once and observe if E40 clears. If it clears but returns during operation, the control board RAM is intermittently failing.
Check for supply voltage quality issues
Measure supply voltage for transients or instability that could be causing repeated memory corruption.
Contact AHT service for control board replacement
E40 indicates a hardware memory fault on the control board requiring replacement by an AHT-authorized technician.
When to call a professional
E40 is a control board hardware fault requiring replacement by an AHT-authorized technician. Do not continue operating the cabinet with an active E40. Contact AHT service 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
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
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