Audi A8 1994 - Page 80

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2.2.4 A/C Pressure/Temperature Sensor -
G395-
The A/C pressure/temperature sensor is installed instead of the
High pressure sensor -G65- .
The A/C Pressure/Temperature Sensor -G395- (housing color
gray at this time) and the High Pressure Sensor -G65- (housing
color black at this time) differ only in color at this time, correct
allocation must therefore be observed when replacing (part num‐
ber. Refer to Electronic Parts Catalog (ETKA). As these two
sensors emit different signals, the relevant control module can
only evaluate the signal to which it has been matched. Refer to
⇒ Heating and Air Conditioning; Rep. Gr. 87 ; Description and
Operation (vehicle-specific repair manual).
When voltage is applied, the A/C pressure/temperature sensor -
G395- exchanges information with the control module via the air
conditioner databus system (“LIN-Bus“). The relevant control
module uses this information to calculate the pressure and tem‐
perature in the refrigerant circuit and any faults detected are
signaled to the control module.
The temperature measured by the A/C pressure/temperature
sensor differs from the actual refrigerant temperature in the re‐
frigerant circuit because of the A/C pressure/temperature sensor
design and its component location. Because of this, it is not cur‐
rently evaluated and is not used to regulate the A/C system. Refer
to ⇒ Heating and Air Conditioning; Rep. Gr. 87 ; Description and
Operation (vehicle-specific repair manual).
This information is used for example by the Climatronic Control
Module -J255- to calculate the pressure in the refrigerant circuit
and to actuate the downstream control modules (coolant fan con‐
trol module, Engine Control Module etc.) via the data bus system.
These control modules control the radiator fan the motor. Refer
to ⇒ Heating and Air Conditioning; Rep. Gr. 87 ; Description and
Operation (vehicle-specific repair manual).
2.2.5 A/C Refrigerant High Pressure Switch -
F23-
Function
Switches the coolant fan to the next higher level when the pres‐
sure in the refrigerant circuit increases (approximately 16 bar).
2.2.6 A/C Refrigerant High Pressure Switch -
F118-
Function
Switches off A/C compressor when there is excessive pressure
in the refrigerant circuit (approximately 32 bar).
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Refrigerant R134a Servicing - Edition 01.2011
76 Rep. Gr.00 - General, Technical Data