audi Workshop Repair Guides

Audi Workshop Service and Repair Manuals

ABOUT US
Test step "6” > < Pin assignment at high-pressure sender G65

A4 Cabriolet Mk2

Pressure signal from high-pressure senderG65
   
Pressure signal from high-pressure sender -G65-
-A- Pressure on high-pressure end of refrigerant circuit in bar (absolute)
-B- Ratio of square-wave signal
-C- Characteristic curve
  Note
t  The operating and display unit, Climatronic control unit -J255- switches on the compressor (by way of actuation of the air conditioning system compressor regulating valve -N280-) in the case of a ratio of greater than 12 % (corresponding to approx. 1.8 bar absolute pressure) and less than 87.5% (corresponding to approx. 32 bar absolute pressure) if there is no compressor shutoff criterion.
t  If the signal ratio is less than 12 % or greater than 87.5%, the compressor is not switched on (the air conditioning system compressor regulating valve -N280- is not actuated).
t  The signal ratio and the pressure calculated by the operating and display unit, Climatronic control unit -J255- are displayed in the measured value block → Chapter (display group “001”).
  A87-0376
t  At absolute pressure, 0 bar corresponds to an absolute vacuum. Normal ambient pressure thus corresponds to roughly 1 bar absolute. On the scales of most pressure gauges, 0 bar corresponds to an absolute pressure of one bar (can be seen from -1 mark below 0).
t  The operating and display unit, Climatronic control unit -J255- transmits the request for activation of the radiator fan(s) -V7- by way of the convenience data bus system to the engine control unit, which then causes the radiator fan control unit -J293- to switch on the radiator fan(s) -V7-:
t  Depending on the version of the operating and display unit, Climatronic control unit -J255-, the radiator fan is either switched on immediately in air conditioning mode when the compressor is activated or the radiator fan is only actuated on exceeding a pressure of approx. 9 bar in the refrigerant circuit.
t  The operating and display unit, Climatronic control unit -J255- transmits the request for increased radiator fan -V7- speed by way of the convenience data bus system to the engine control unit:
t  On vehicles with diesel engine, the radiator fan(s) -V7- is/are 100% actuated at present as of a pressure of 16 bar in the refrigerant circuit.
t  For vehicles with petrol engine, 100% is currently only requested at a pressure of approx. 26 bar in the refrigerant circuit.
t  The signal generated by the high-pressure sender -G65- is also used for engine control. The operating and display unit, Climatronic control unit -J255- transmits the information via the convenience data bus system to the engine control unit (torque required for driving compressor is governed by pressure in refrigerant circuit). Depending on the version of the engine control unit, the signal is displayed as a ratio in the measured value block → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051, → Injection and ignition system; Rep. Gr.01 or → Diesel direct injection and glow plug system; Rep. Gr.01
  A87-0376

Test step "6” > < Pin assignment at high-pressure sender G65