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Air-conditioning, climate control > < Install the holder

Leon Mk2

Check the activation signal for the Compressor regulation valve, air conditioning N280
Check the activation signal for the Compressor regulation valve, air conditioning -N280-
–  Switch ignition OFF.
–  Remove the upper protective cover of the engine (e.g. in vehicles with 4-cyl. engine, the connector can be accessed from above) → Engine, mechanics; Rep. gr.13.
–  Remove the sound proofing → Bodywork, exterior fitting work; Rep. gr.50.
   
–  Disconnect the connection to the Compressor regulation valve, air conditioning -N280- on pin -1-.
  A10-1637
–  Re-establish the connection using the adapter cable from the auxiliary measurement set -VAG 1594C- between the connector -A- and the connector -B- on the regulation valve.
  Note
t  During the activation of the Compressor regulation valve, air conditioning -N280-, the current measured by the control and indication panel Climatronic control unit -J255-/Air conditioning control unit -J301- is displayed in the measurement values block → Vehicle diagnostic, testing and information system VAS 5051.
  A87-0390
t  Use can also be made of an improvised adapter cable for this test. This requires, for example, one connector -A- or -B- each (with original part number 1J0 973,702 and 1J0 973,802 and the corresponding plug contacts), two commercially available sockets for banana plugs -C- and two wires with a cross section of 0.5 mm2.
  A87-0389
–  Connect the measurement cables -VAS 5051/8-to the adapter cables.
–  Test cable(signal) to contact -2-.
–  Test cable (screen, earth) to contact -1-.
–  Adjust in the self diagnosis -VAS 5051- the operation mode: DSO (digital memory oscilloscope).
–  Adjustment 5V/Div = 0.5ms/Div (5 volts DC and 0.5 milliseconds per unit).
–  Start engine.
–  Adjust the temperature on the passenger and driver sides in the Climatronic control unit -J255-/Air conditioning control unit -J301-.
Vehicles fitted with Climatronic:
–  Activate and deactivate in the Climate control unit -J255- using the keys „Auto“ and „Off/On“ or „Econ“, the activation of the Compressor regulation valve, air conditioning -N280-.
Vehicles fitted with Climatic:
–  Activate and deactivate in the Air conditioning control unit -J301- using the keys „AC“ and selecting the speed „1“ for the Fresh air blower -V2-, the activation of the Compressor regulation valve, air conditioning -N280-.
The adjustment function of the Climatronic control unit -J255-/Air conditioning control unit -J301- is displayed on the oscilloscope screen:
–  In operation mode „OFF“ or „Econ“ without any rectangular wave signal (the regulation valve is not activated).
Vehicles fitted with Climatronic:
  A87-0390
–  In the operation mode „Auto“ with the temperature control at the minimum, there is a rectangular wave signal with a pulse width -A- of between 75 % and 100% (the regulation valve is activated).
Vehicles fitted with Climatic:
–  With the button „AC“ pressed, the speed „1“ of the Fresh air blower -V2- selected and with the temperature control at minimum, there is a rectangular wave signal with a pulse width -A- of between 75 % and 100% (the regulation valve is activated).
  Note
t  The figure shows a signal with a duty cycle of approx. 80%.
t  The amplitude of the pulse -A- depends on the desired cooling power, the on-board voltage, etc. (in the field -A-, the flow is controlled via air conditioning system compressor regulating valve -N280- from the Climatronic control unit -J255-/air conditioning control unit -J301-.
t  The length -B- of the signals is always 2 milliseconds (corresponding to a frequency of 500 Hertz).
  A87-0374
t  The duty signal is the result of the relationship between the width of the pulse -A- and the length of the signal -B-.
–  Depending on the adjustment in the Climatronic control unit -J255-/Air conditioning control unit -J301- and the magnitudes of the environment conditions measured, the amplitude of the rectangular wave signal (duty cycle between 100% and more than 30%, the regulation valve is activated in such a way that enough power is directed to the compressor to reach the specified temperatures).
  Note
t  With the setting of the lowest temperature, the air conditioning system compressor regulating valve -N280- is controlled in such a way that the maximum permissible flow of current flows with approx. 0.65 A through the air conditioning system compressor regulating valve -N280- (highest power of the compressor).
t  During regular operation, the controlling period depends on the required cooling output, the on-board voltage, etc. However, the controlling continues until an average current intensity of approx. 0.3 A flows.
  A87-0374

Air-conditioning, climate control > < Install the holder