Volkswagen Golf 1999 Service Manual page 4059

Pressures, checking on vehicles
Note:
- 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
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- Expansion valve malfunctioning
Possible cause
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found at one component:
- If hose or pipe is kinked or
constricted, replace this
component.
- In the event of an obstruction
flush refrigerant circuit with
compressed air and nitrogen
- Re-charge refrigerant circuit.
- Repeat test.
- If no malfunction can be found
- Flush refrigerant circuit with
compressed air and nitrogen.
- Re-charge refrigerant circuit.
- Repeat test, if function is not
- Discharge refrigerant circuit.
- Replace expansion valve and
receiver.
- Re-charge refrigerant circuit.
Corrective action
13/2/2005