Volkswagen Golf 1999 Service Manual page 4003

General information on refrigerant circuit
When a voltage is applied, the high pressure sensor
generates a square wave signal or a data telegram. This
signal changes along with pressure in the system.
The downstream control modules (Coolant Fan Control
(FC) Control Module, Engine Control Module (ECM), A/C
Control Head E87 or Climatronic Control Module J255 ,
etc.) use this signal to calculate pressure in the refrigerant
circuit and accordingly to activate coolant fans and motor,
A/C Clutch N25 or to change activation of A/C Compressor
Regulator Valve N280 .
A/C Pressure/temperature Sensor G395
Warning!
There is a danger of ice-up.
Refrigerant may leak out if refrigerant circuit is not
discharged.
Refrigerant must be extracted before removing the A/C
Pressure/temperature Sensor G395 .
This A/C Pressure/temperature Sensor G395 is installed
instead of High Pressure Sensor G65 or A/C Pressure
Switch F129 .
The pressure signal is continuously checked, where the
temperature signal is only checked at temperatures above
0 C.
The Climatronic Control Module J255 operates with this
information and accordingly controls the coolant fans and
activation of the A/C Compressor Regulator Valve N280 .
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13/2/2005