Volkswagen Golf / Golf GTI / Jetta. Manual — part 1015

- Low pressure in line with value in
graph.

- Required cooling output is not
attained.

- High pressure normal.

- Low pressure too low (see
graph).

- Required cooling output is not
attained.

- High pressure normal.

- Low pressure too low (see
graph).

- Required cooling output is not
attained.

- Not enough refrigerant in
refrigerant circuit.

- Extract refrigerant from
refrigerant circuit.

- If quantity of refrigerant extracted
is substantially less than specified
capacity.

- Localize leak using leak detector
and eliminate.

- Re-charge refrigerant circuit.

- Repeat test.

- If quantity of refrigerant extracted
roughly corresponds to specified
capacity:

- Expansion valve malfunctioning - Replace expansion valve.

- Re-charge refrigerant circuit.

- Repeat test.

Note:

- If no malfunction is found in
relation to this complaint, flush
refrigerant circuit with compressed
air and nitrogen.

- Check measured values of
Evaporator Vent Temperature
Sensor G263 and activation of A/C
Compressor Regulator Valve
N280 . If measured value of High
Pressure Sensor G65 is not OK,
evaporator may ice up or cooling
output is not attained.

- If the function of the air
conditioning system is not OK
when the test is repeated after
replacing expansion valve, re-
install old expansion valve and
flush refrigerant circuit with
compressed air and nitrogen.
Then replace A/C compressor and

Pressures, checking on vehicles

13/2/2005

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

Possible cause

Corrective action

- High pressure only increases
slightly above pressure with
engine stopped.

- Low pressure only drops slightly.

- Required cooling output is not
attained.

- Activation of A/C Compressor
Regulator Valve N280
malfunctioning

- Check activation of
Compressor Regulator Valve
N280 .

- A/C compressor malfunctioning. - Discharge refrigerant circuit.

- Replace compressor.

- Re-charge refrigerant circuit.

- High pressure increases above
specification.

- Low pressure quickly drops to
value in graph or below.

- Required cooling output is not
attained.

- Activation of A/C Compressor
Regulator Valve N280
malfunctioning

- Check activation of
Compressor Regulator Valve
N280 .

- Constriction or obstruction in
refrigerant circuit

- Run hand over refrigerant circuit
to check for differences in
temperature

- If difference in temperature is

Pressures, checking on vehicles

13/2/2005

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 OK.

- Expansion valve malfunctioning - Discharge refrigerant circuit.

- Replace expansion valve and
receiver.

- Re-charge refrigerant circuit.

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

Possible cause

Corrective action

Pressures, checking on vehicles

13/2/2005

specification

- High and low pressure normal at
first, after some time high pressure
increases above specification.

- After a time, low pressure drops
to value in graph or below.

- Required cooling output is no
longer attained.

- Activation of A/C Compressor
Regulator Valve N280
malfunctioning

- Check activation of
Compressor Regulator Valve
N280 .

- High and low pressure normal at
first, after lengthy driving time, low
pressure drops below specification
(evaporator ices up).

- Moisture in refrigerant circuit

- Discharge refrigerant circuit.

- Flush refrigerant circuit with
compressed air and nitrogen.

- Replace receiver with dryer.

- Evacuate refrigerant circuit for at
least 3 hours.

- Re-charge refrigerant circuit.

- Repeat test.

Note:

- If problem involving moisture in
refrigerant circuit only occurs after
a lengthy operating period or only
infrequently (low pressure drops
below specification and evaporator
ices up), it is sufficient to replace
the dryer in the receiver. Adjust
quantity of refrigerant oil.
Refrigerant circuit is then to be
evacuated for at least 3 hours.

- It is not initially necessary to
flush the refrigerant circuit with
compressed air and nitrogen when
this problem occurs since
normally, there is only a small
quantity of moisture in the system
which can be removed by lengthy
evacuation.

- With this malfunction, evaporator
may ice up although quantity of
refrigerant in circuit is OK.

Possible deviation from

specification

Possible cause

Corrective action

Pressures, checking on vehicles

13/2/2005