9-5 Aero (9600) L4-2.3L Turbo (B235) HO (2000)
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Control Module HVAC: Description and Operation
Control Module
Control Module
The control module is an integral part of the ACC unit and is activated by +15 or the parking heater input. When the control module is active, the display
lights up and diagnostic communication is possible. When the module has been activated by +15, it can assume the following modes:
Engine stationary
If the engine is stationary, there is no coolant circulating through the heat exchanger, the A/C compressor is stationary and the generator is not charging.
This means that the system cannot regulate the climate, that the system should not consume current unnecessarily and that there is a risk that a stepping
motor may miss a step due to low battery voltage if the starter motor should be engaged. For these reasons, the control module selects rear window
heating off, fan current 5 A, air recirculation off and all stepping motors off.
Engine running
As soon as the engine has started, the control module regulates all the functions automatically as long as no manual functions have been selected or user
programming performed.
Ignition OFF
When the ignition is turned off, the display goes out: no buttons work, all the stepping motors are turned off and air recirculation off is selected after 10
seconds. Diagnostics communication remains active if it was active when the ignition was turned off, but it cannot be restarted.
The control module processor is active for a further 10 minutes. If the ignition is turned on within these 10 minutes, the control module will retain any
manual selections made when the car was last driven. After 10 minutes, the control module starts in AUTO or user programming mode.
If the power supply drops below 9.5 V and the starter motor is not turning, the display will show OFF until the voltage exceeds 10 V.
Programming
