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O-rings for refrigerant circuit > < Pin allocation on the High pressure sender G65

Leon Mk2

The pressure signal of the High pressure sender G65.
The pressure signal of the High pressure sender -G65-.
   
-A- Pressure in the high pressure side of the refrigeration agent circuit in bar (absolute pressure)
-B- Provides the duty cycle of the rectangular wave signal
-C- Characteristic curve
  Note
t  The Climatronic control unit -J255-/Air conditioning control unit -J301- activates the compressor when there is no condition to deactivate the compressor (activating the Compressor regulation valve, air conditioning -N280-) → Vehicle diagnosis, testing and information system VAS 5051.
t  When the duty cycle is more than 12 % (equal to about 1.2 bar of absolute pressure) and lower than 78 % (equal to about 32 bar of absolute pressure).
t  If duty cycle is less than 12 % or greater than 78 %, the compressor is not activated (the Compressor regulation valve, air conditioning -N280- is not activated).
t  The duty cycle and the calculated pressure on the control and indication panel Climatronic control unit -J255-/Air conditioning control unit -J301- is displayed on the measurement values block → Vehicle diagnosis, testing and information system VAS 5051.
t  In absolute pressure 0 bar means a vacuum. The normal atmospheric temperature is, thus, about 1 bar of absolute pressure. In general most manometer scales represent atmospheric pressure as 0 bar meaning an absolute pressure of 1 bar (this can be recognised if there is a -1 on the scale).
  A87-0340
t  The Climatronic control unit -J255-/Air conditioning control unit -J301- sends a signal along the comfort data bus to the engine control unit, depending on the pressure calculated in the refrigeration circuit, while the compressor is activated, to request a higher refrigerant ventilator speed. The request calculated by the Climatronic control unit -J255-/Air conditioning control unit -J301- is displayed on the measurement values block → Vehicle diagnosis, testing and information system VAS 5051.
t  Currently, the request for a higher refrigerant ventilation speed is sent for the following duty cycle:
t  Pressure in refrigerant circuit in bar lower than 9 bar (6 bar if the pressure was above 9 bar) - no request.
t  Pressure in refrigerant circuit in bar higher than 9 bar (6 bar) up to about 20 bar, depending on the pressure - request 30 % to 100%.
t  Pressure in refrigerant circuit in bar higher than 20 bar - request 100 %.
t  The signal generated by the High pressure sender -G65- may also be used for engine management. The control and indication panel Climatronic control unit -J255-/Air conditioning control unit -J301- sends the information over the comfort system data bus to the engine control unit (the torque required for compressor operation depends on the pressure in the refrigeration circuit). Depending on engine control unit version, the signal is displayed as duty cycle in measurement value block → Vehicle diagnosis, testing and information system VAS 5051
  A87-0340
On the oscilloscope screen (for example in the self diagnosis -VAS 5051-) this image appears when the limit conditions are fulfilled:
–  When the ignition is turned on (positive on the pin “3” and earth on the pin “1” on the High pressure sender -G65-).
–  Adjustment on the oscilloscope: 5 V/Div. = (5V per DC voltage unit) 5 ms/Div. (5 milliseconds per unit).
–  Measurement cable (signal cable) on the pin “2” connected to the High pressure sender -G65-.
–  Measurement cable (screened) to contact “1” (earth on High pressure sender -G65-).
  Note
t  The diagram shows the signal output in case of refrigerant circuit pressure of about 7 bar absolute pressure, corresponding to a duty cycle of about 25 % (correct when the compressor is deactivated, the atmospheric temperature is 30°C and the refrigeration circuit is correctly filled).
  A87-0375
t  The amplitude of the pulses -A- depends on the pressure in the refrigeration circuit (if the pressure increases, the margin is made wider -A-).
t  The length -B- of the signals is always 20 milliseconds (corresponding to a frequency of 50 Hertz).
t  The duty signal is the result of the relationship between the width of the pulse -A- and the length of the signal -B-.
  A87-0375
t  For this test, the test cables from the auxiliary measurement set -VAG 1594C- may be used as can a cable adapted for this purpose. This requires, for example, one connector -A- and -B- each (part number 1J0 973 703 and 1J0 973,803 and the corresponding plug contacts), two commercially available sockets for banana plugs -C- and three cables with cross section 0.5 mm2.
  A87-0638

O-rings for refrigerant circuit > < Pin allocation on the High pressure sender G65