O-Rings For Refrigerant Circuit - Audi Air conditioning 2003 A8 Workshop Manual

– Depending on the pressure calculated in the refrigerant circuit,
the front operating and display unit, Climatronic control unit -
J255- transmits the request for increased radiator fan speed
to the engine control unit via the convenience data bus system
with the compressor actuated. The fan speed determined by
the front operating and display unit, Climatronic control unit -
J255- is displayed in the measured value block ⇒ "Guided
fault-finding" function of vehicle diagnostic, testing and infor‐
mation system VAS 5051.
This pattern will appear on the oscilloscope screen (e.g. on the
vehicle diagnostic, testing and information system -VAS 5051 A- )
if the following conditions are satisfied.
– Ignition on (positive at contact „3" and earth at contact „1" at
high-pressure sender -G65- )
– Setting on oscilloscope: 5 V/div. DC (5 V per unit DC voltage)
5 ms/div. (5 milliseconds per unit)
– Test lead (signal wire) connected to contact „2" at high-pres‐
sure sender -G65-
– Test lead (screen) connected to contact „1" (earth at high-
pressure sender -G65- )
Note
Use can be made for connection of the high-pressure sender
♦
-G65- of test leads from the Adapter set -V.A.G 1594 C- for
example.
The illustration shows the signal transmitted at a refrigerant
♦
circuit pressure of approx. 7 bar absolute, corresponding to a
signal ratio of approx. 25% (level occurring with compressor
not running, ambient temperature of 30 °C and refrigerant cir‐
cuit charged).
The pulse width -A- is governed by the pressure in the refrig‐
♦
erant circuit (area -A- becomes broader as pressure increa‐
ses).
The signal distance -B- is always 20 milliseconds (correspond‐
♦
ing to a frequency of 50 hertz).
The signal ratio is derived from the ratio of pulse width -A- to
♦
signal distance -B-.
3.4

O-rings for refrigerant circuit

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♦ Always replace, only to be used once.
♦ Moisten with refrigerant oil before fitting.
♦ Ensure correct positioning on pipe/in groove.
♦ Ensure cleanliness when working.
Audi A8 2003 ➤
Air conditioning - Edition 09.2010
3. Servicing refrigerant circuit
13