Audi Air conditioning 2003 A8 Workshop Manual page 23

Note
Actuation of the air conditioner compressor regulating valve -
♦
N280- and the current measured by the front operating and
display unit, Climatronic control unit -J255- which flows via the
air conditioner compressor regulating valve -N280- are dis‐
played in the measured value block of the front operating and
display unit, Climatronic control unit -J255- ⇒ "Guided fault-
finding" function of vehicle diagnostic, testing and information
system VAS 5051.
An adapter cable can also be produced for this test. This re‐
♦
quires, for example, one connector -A- and -B- each (with 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 mm
– Connect the probe -VAS 5051/8- to the adapter leads.
– Test lead (signal wire) to contact -2-
– Test lead (screen, earth) to contact -1-
– On the vehicle diagnostic, testing and information system - Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
VAS 5051 A- , set Measurement mode: DSO (digital storage
with respect to the correctness of information in this document. Copyright by AUDI AG.
oscilloscope).
– Settings 5V/div DC, 0.5 ms/div (5 V DC and 0.5 milliseconds
per unit)
– Start the engine.
– On the front operating and display unit, Climatronic control unit
-J255- , set the temperature to „Lo".
– On the front operating and display unit, Climatronic control unit
-J255- , press the buttons „Auto" and „Off/On" to activate and
deactivate the air conditioner compressor regulating valve -
N280- .
The display on the oscilloscope screen will be as follows depend‐
ing on the setting on the front operating and display unit, Clima‐
tronic control unit -J255- :
– In „OFF" mode: No square-wave signal (regulating valve is not
actuated)
Air conditioning - Edition 09.2010
2
.
3. Servicing refrigerant circuit
Audi A8 2003 ➤
17