Audi Q7 2007 Repair Manual page 31

♦ Currently, the Refrigerant Temperature Sensor - G454- is not
installed in all vehicles (from start of production through the
discontinuation from 11.2007 on vehicles with a 6-cylinder TDI
engine or an 8-cylinder engine). Refer to Wiring diagrams,
Troubleshooting and Component locations.
♦ The measured value from the Refrigerant Temperature Sen‐
sor - G454- is not evaluated by the Climatronic Control Module
- J255- front A/C control head ("adaptation" has shut off the
evaluating). The missing refrigerant temperature sensor -
G454- will be stored as a fault because the vehicle is supposed
to have a refrigerant temperature sensor -G454- (solution:
change the adaptation to "Basis" front A/C control head. Use
the Vehicle Diagnostic Tester via the "Guided Fault Finding"
function. Or, if the vehicle has a "Comfort" front A/C control
head, for example, connect a refrigerant temperature sensor
-G454- , which is OK, to the vehicle wiring harness and secure
it to the vehicle (without removing the faulty refrigerant tem‐
perature sensor -G454- and installing a new refrigerant tem‐
perature sensor -G454- ).
♦ The Refrigerant Temperature Sensor - G454- -B- (with tem‐
perature dependent resistor) is installed into refrigerant line
-C- (high pressure side of refrigerant circuit) between com‐
pressor and condenser). For removing and installing, refer to
⇒ "15.5 Refrigerant Temperature Sensor G454 , Removing
and Installing", page 255
♦ The Climatronic Control Module - G454- evaluates the meas‐
ured value from the Climatronic Control Module - J255- -B-
only under certain conditions, even if "adaptation" is not
switched off.
Note
In the refrigerant circuit, there is essentially a direct relation‐
♦
ship between temperature and pressure, if there should be too
little refrigerant in the refrigerant circuit (less than 50% of the
specified capacity), the temperature in the refrigerant circuit
rises more strongly than intended for this pressure when A/C
system is operating.
The front Climatronic Control Module - J255- evaluates the
♦
temperature in the refrigerant circuit and switches the com‐
pressor off in the event the temperature rises above the value
that was stored for this operating condition at the outside tem‐
perature currently measured.
In addition to insufficient refrigerant, a soiled condenser or
♦
faulty actuation of the coolant fans may also be the cause for
excessive refrigerant temperature.
For removing and installing the Refrigerant Temperature Sen‐
♦
sor - G454- , refer to
⇒ "15.5 Refrigerant Temperature Sensor G454 , Removing
and Installing", page 255
Heating, Ventilation and Air Conditioning - Edition 04.2013
.
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with respect to the correctness of information in this document. Copyright by AUDI AG.
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Audi Q7 2007 ➤
25
3. Refrigerant Circuit