S4 Quattro Wagon V8-4.2L (BHF) (2008)
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‹› The Climatronic control module (J255) A/C control head transmits the request to activate the coolant fan(s) (V7) via the comfort data bus system
to the engine control module. The engine control module then switches the coolant fan(s) (V7) on via the coolant fan control module (J293):
‹› Depending on the version of the Climatronic control module (J255) A/C control head, the coolant fan is switched on immediately in the A/C
system mode when the compressor is switched on or the coolant fan is only activated when a pressure of approx. 9 bar is exceeded in the
refrigerant circuit.
‹› The Climatronic control module (J255) A/C control head transmits the request for an increased speed of the coolant fan(s) (V7) via the comfort
data bus system to the engine control module:
‹› 100% is currently first required at a pressure of approx. 26 bar in the refrigerant circuit.
‹› The signal generated from High Pressure Sensor ( G65) is also used to control the engine. The Climatronic control module (J255) A/C control
head sends the information to the engine control module via the comfort data bus system (the necessary torque to drive the compressor depends on
the pressure in the refrigerant circuit). Depending on the version of the engine control module, the signal is displayed in the measured value block
as a duty cycle. Refer to => Vehicle Diagnosis, Testing and Information System VAS 5051 in the "guided fault finding" function.
