Electronic Control Module (Ecm) - Aston Martin DB7 Workshop Manual

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Air Conditioning
Electronic Control Module
Electronic Control Module (ECM)
The Electronic Control Module (ECM) is located on the right hand side of the heater unit.
The ECM has a digital microprocessor that allows the air conditioning system to maintain the selected in-car
conditions. To do this it compares the signals from the in-car controls with those it receives from the system
temperature sensors and feedback devices. On the basis of these comparisons it makes appropriate voltage changes
to vary the blower motor speed, flap position and the state of other solenoids that effect the selected temperature
demand.
The ECM is a non-serviceable component but may be interrogated for system testing. Care must be exercised when
connecting the test equipment as the ECM may be irreparably damaged should any ofthe test pins be shorted or bent.
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1. Electronic control module (ECM)
2. Differential temperature control
3. Temperature control
4. Fan speed control
5. Ambient temperature sensor
6. Motorised in-car aspirator
7. Evaporator temperature sensor
8. Coolant temperature switch
9. Lower flap feedback potentiometer
10. Upper flap feed back potentiometer
11. Left hand blower motor feedback
12. Right hand blower motor feedback
13. High speed relay
14. High speed relay
15. Compressor clutch
16. Blower motor
17. Blower motor
18. Lower flap servo motor
19. LIpper flap servo motor
20. Defrost vacuum solenoid
21. Auto re-circulation vacuum solenoid
22. Centre vent vacuum solenoid
23. Water valve vacuum solenoid
24. Air conditioning function switch
May 1996
8-19