Volkswagen Golf 1999 Service Manual page 4058

Pressures, checking on vehicles
receiver.
- With this malfunction, evaporator
may ice up although quantity of
refrigerant in circuit is OK.
- If expansion valve is
malfunctioning (permanently
closed or does not open
sufficiently), A/C Compressor
Regulator Valve N280 is actuated
to maximum output and low
pressure drops to value in graph
or below (compressor draws off
refrigerant from low-pressure
side). As however refrigerant
cannot flow via expansion valve,
cooling output is not attained and
high pressure may also not
increase or only increase slightly
due to the absence of energy
conversion.
Possible deviation from
specification
- High pressure only increases
slightly above pressure with
engine stopped.
- Low pressure only drops slightly.
- Required cooling output is not
attained.
- High pressure increases above
specification.
- Low pressure quickly drops to
value in graph or below.
- Required cooling output is not
attained.
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Possible cause
- Activation of A/C Compressor
Regulator Valve N280
malfunctioning
- A/C compressor malfunctioning. - Discharge refrigerant circuit.
- Activation of A/C Compressor
Regulator Valve N280
malfunctioning
- Constriction or obstruction in
refrigerant circuit
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Corrective action
- Check activation of
Compressor Regulator Valve
N280 .
- Replace compressor.
- Re-charge refrigerant circuit.
- Check activation of
Compressor Regulator Valve
N280 .
- Run hand over refrigerant circ
to check for differences in
temperature
- If difference in temperature is
13/2/2005