Audi A3 1997 Manual page 92

Audi A3 1997 ➤
Heating, Air Conditioner - Edition 06.2000
◆ -> Control unit -J293 switches radiator fan -V7 to speed 2:
- As soon as the refrigerant circuit pressure exceeds 16 bar (duty cycle exceeds 45%). If the pressure
drops below 12.5 bar (duty cycle drops below 37%), the fans are switched back to 1st speed.
- Refrigerant thermoswitch -F18 closed.
- As soon as a positive signal from the engine control unit is present (only in vehicles with map-controlled
engine cooling).
◆ The control unit -J293 switches radiator fans -V7 to 1. speed:
- As soon as a signal from the -E87 for switching on of the compressor is present.
- When thermo switch -F54 is closed.
- As soon as a positive signal from the engine control unit is present (only in vehicles with map-controlled
engine cooling and in vehicles with 81 KW diesel engine).
◆ The signal generated by high-pressure sensor -G65 is also used for engine control (the required compressor
drive torque is governed by the refrigerant circuit pressure). Depending on the engine control unit version,
the signal in the measured value block is displayed as duty cycle.
=> Relevant Workshop Manual Injection and Ignition system
Check signal from -G65
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- -> Connect test lead of one oscilloscope to the signal wire of high-pressure sensor -G65 (=> Page
step 4).
This display appears on the oscilloscope screen if the following conditions have been satisfied.
- Ignition switched on (positive and earth applied at sender -G65)
- Oscilloscope setting:
2 V/Div. = (2 V DC per unit)
5 ms/Div. (5 milliseconds per unit)
86
01 - Self-diagnosis, Electrical check
with respect to the correctness of information in this document. Copyright by AUDI AG.
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