Audi Q7 2007 Repair Manual page 39

– Turn the A/C Compressor Regulator Valve - J255- on and off
on the Climatronic Control Module - N280- front A/C control
head, for example by pressing the buttons
Shown on screen of oscilloscope, depending on setting of Clima‐
tronic Control Module - J255- front A/C control head:
– No square wave signal ( A/C Compressor Regulator Valve -
N280- is not activated) for operating mode "OFF" and "Econ"
or "A/C off".
– A square wave signal with an impulse width -A- between 75%
and 100% (regulator valve is activated) for operating mode
"Auto" (or with compressor switched on) and temperature set‐
ting "Lo".
Note
The illustration shows a signal with a duty cycle of approxi‐
♦
mately 80%.
Impulse width -A- is dependent on desired cooling perform‐
♦
ance, vehicle voltage etc. (over the width of region -A-, voltage
is regulated via A/C Compressor Regulator Valve - N280- by
front A/C control head Climatronic Control Module - J255- ).
The signal distance -B- is always two milliseconds (corre‐
♦
sponds to frequency of 500 Hertz).
The duty cycle is determined by the ratio of impulse width
♦
-A- and signal distance -B-.
– The impulse width of the square wave signal changes (duty
cycle between 100% and greater than 30%, regulator valve is
activated so that required compressor output is obtained to
reach the specified temperatures) depending on setting at the
Climatronic Control Module - J255- front A/C control head and
measured surrounding conditions.
Note
At setting of maximum cooling performance (for example, op‐
♦
erating mode "Auto" and temperature setting "Lo" on "Comfort"
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
version), A/C Compressor Regulator Valve - N280- is activa‐
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
ted so that the maximum permissible current of approximately
0.65 A flows via A/C Compressor Regulator Valve - N280-
(maximum compressor output).
In control mode, actuation time is governed by required cool‐
♦
ing output and vehicle electrical system voltage, for example.
It is however always of sufficient duration to achieve a mean
current of 0.3 A.
Heating, Ventilation and Air Conditioning - Edition 04.2013
or .
ECON AC
Audi Q7 2007 ➤
33
3. Refrigerant Circuit