Audi Air conditioning 2003 A8 Workshop Manual page 130

Audi A8 2003 ➤
Air conditioning - Edition 09.2010
Note
At absolute pressure, 0 bar corresponds to an absolute vac‐
♦
uum. Normal ambient pressure thus corresponds to roughly 1
bar absolute. On the scales of most pressure gauges, 0 bar
corresponds to an absolute pressure of one bar (can be seen
from -1 mark below 0).
The pressure in the refrigerant circuit is governed by the am‐
♦
bient temperature. Due to the radiation of heat by components
(e.g. the radiator fan), the pressure displayed with a warm en‐
gine is slightly higher than that given for the corresponding
ambient temperature.
If the displayed pressure in the refrigerant circuit is lower than that
given in the table:
– Check the signal of the air conditioner high-pressure sender -
G65- ⇒ page 10 .
– If no fault is found at the air conditioner high-pressure sender
-G65- , there is not enough refrigerant in the circuit. Take the
vehicle to a workshop equipped with the necessary tools
where the work can be performed by appropriately qualified
personnel ⇒ Air conditioner with refrigerant R134a .
If the pressure in the refrigerant circuit is OK:
– Switch on the compressor by selecting „Auto" mode on the
front operating and display unit, Climatronic control unit -J255-
or on the MMI (Multi Media Interface).
– Select „Lo" temperature (for driver and front passenger side)
on the front operating and display unit, Climatronic control unit
-J255- .
– Set the air outflow direction on the front operating and display
unit, Climatronic control unit -J255- to „dash panel vents".
– Select the „Reading measured value block" function ⇒ "Gui‐
ded fault-finding" function of vehicle diagnostic, testing and
information system VAS 5051.
– Check the diagnosis tester display in the various display
zones:
– The display zone for actuation of the air conditioner compres‐
sor regulating valve -N280- shows a duty cycle greater than
30% ( -N280- actuated, compressor switched on).
– The display zone for the current to the air conditioner com‐
pressor regulating valve -N280- shows a current greater than
0.3 A (current flowing via -N280- , compressor switched on).
– The pressure measured by the high-pressure sender -G65-
and displayed increases above the value with the compressor
switched off.
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Rep. gr.87 - Air conditioning system
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