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O-rings for refrigerant circuit > < Pin allocation on the High pressure sender (00819) G65

Leon Mk2

The pressure signal from the High pressure sender (00819)G65
The pressure signal from the High pressure sender (00819) -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 (01320) -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 (01232) -N280-) → Vehicle diagnosis, testing and information system VAS 5051.
t  With a duty cycle of above 12% (equivalent to approx. 1.2 bar of absolute pressure) and below 78% (equivalent to approx. 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 (01232) -N280- is not activated).
t  The duty cycle and the calculated pressure on the control and indication panel Climatronic control unit (01320) -J255-/Air conditioning unit -J301- is displayed on the measurement values block → Vehicle diagnosis, testing and information system VAS 5051.
t  In absolute pressure, 0 bar corresponds to a total vacuum. Standard atmospheric pressure is therefore at approx. 1 bar of absolute pressure. On the scales of the majority of pressure gauges, 0 bar corresponds to an absolute pressure of one bar (this can be seen in the indicator of -1 below 0).
  A87-0340
t  The Climatronic Control unit (01320) -J255-/Air Conditioning control unit -J301- depending upon the pressure calculated in the coolant circuit with the compressor activated, send through the comfort system data bus the request for a higher fan speed for the coolant to the engine control unit. The request calculated by the Climatronic control unit (01320) -J255-/Air Conditioning control unit -J301- is displayed on the measurement value 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 the coolant circuit below approx. 9 bar (6 bar, if the pressure was above 9 bar) without request.
t  Pressure in the coolant circuit above approx. 9 bar (6 bar) to approx. 20 bar, depending on the pressure of 30 to 100% request.
t  Pressure in refrigerant circuit higher than approx. 20 bar 100% request.
t  The signal generated by the High Pressure sender (00819) -G65- is also used for the engine management. The control and indication panel Climatronic control unit (01320) -J255-/Air conditioning control unit -J301- sends the information through the comfort system data bus to the engine control unit (the torque required to activate the compressor depends upon the pressure in the coolant circuit). Depending upon the version of engine control unit the signal is displayed on the measurement value block as a duty cycle → Vehicle diagnosis, testing and information system VAS 5051.
  A87-0340
On the oscilloscope (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 (00819) -G65-).
–  Adjustment on the oscilloscope: 5 V/Div. = (5V per voltage unit DC) 5 ms/Div. (5 miliseconds per unit).
–  Measurement cable (signal cable) on the pin “2” connected to the High pressure sender(00819) -G65-.
–  Measurement cable (screen) to contact “1” (earth on High pressure sender (00819) -G65-).
  Note!
t  The figure shows the signal emitted for a coolant circuit pressure of approx. 7 bar of absolute pressure, which corresponds to a duty cycle of apprx. 25% (this is adjusted with the compressor off, an air temperature of 30°C and a correctly filled coolant circuit).
  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 or an adapter cable can be made. 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 of cross section 0.5 mm2.
  A87-0638

O-rings for refrigerant circuit > < Pin allocation on the High pressure sender (00819) G65