Volkswagen Golf / Golf GTI / Jetta. Manual — part 1011

- High and low pressure normal at
first, after some time,

- High pressure increases above
specification

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

- Required cooling output is no
longer attained.

- High pressure normal,

- Low pressure too low (see
graph),

- The required cooling level is
obtained.

Note:

- For the malfunction "high
pressure normal, low pressure too
low" , note the following:

- This malfunction may cause the
evaporator to ice up or the A/C
Refrigerant Low Pressure Switch
F73 to shut off the compressor
although the amount of refrigerant
in the circuit is OK.

Possible deviation from

specification

Possible cause

Corrective action

- High pressure normal or too high

- Low pressure too high (see
graph),

- Compressor noise (particularly
after switch-on)

- Required cooling output is not

Too much
refrigerant in
circuit

- Extract refrigerant from
refrigerant circuit.

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

- Replace A/C compressor.

Pressures, checking on vehicles

13/2/2005

attained.

- If quantity of refrigerant extracted
is substantially greater than
specified capacity:

- Re-charge refrigerant circuit.

- Repeat test.

Note:

- Overfilling with refrigerant oil can
occur if, for example, the
compressor has been replaced
without adjusting the quantity of
refrigerant oil.

Expansion valve and
receiver (with internally
regulated compressor),
checking

Note:

- Connect service station

00-6,

Service station, connecting

.

- Observe test conditions

00-7,

Pressures, checking on vehicles

.

- Set engine speed to 2000 RPM.

- Observe pressure gauge set.

Note:

- Switching pressures and
arrangement of refrigerant circuit
switches are vehicle-specific.

Pressures must be measured at
service connections; component
locations of these connections are
vehicle-specific

Repair Manual, Heating & Air

Conditioning, Repair Group 87 ,

Specified values:

Pressures, checking on vehicles

13/2/2005

High pressure side:

Increasing from initial pressure (on
connecting pressure gauges) to
max. 20 bar.

Low pressure side:

Decreasing from initial pressure
(on connecting pressure gauges)
to value in graph.

A - High pressure in bar

B - Low pressure in bar

C - Permissible tolerance range.

Possible deviation from

specification

Possible cause

Corrective action

- High pressure remains constant
or only increases slightly (above
pressure with engine stopped),

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

- Required cooling output is not
attained.

Not enough
refrigerant in
circuit or
expansion valve
malfunctioning.

- Extract refrigerant from
refrigerant circuit.

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

- Replace expansion valve.

- Re-charge refrigerant circuit.

- Repeat test.

- High pressure normal,

- Low pressure in line with value in
graph,

- Required cooling output is not
attained.

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

- Localize leak using leak detector
and eliminate.

- Re-charge refrigerant circuit.

- Repeat test.

Note:

- If no malfunction can be found
and air conditioner operation is not
OK when test is repeated, flush
refrigerant circuit with compressed
air and nitrogen.

Possible deviation from

Possible cause

Corrective action

Pressures, checking on vehicles

13/2/2005

specification

- High pressure increases above
specification

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

- Required cooling output is not
attained.

- Constriction or obstruction in
refrigerant circuit

- Expansion valve malfunctioning

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

- If difference in temperature is
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 and
replace expansion valve

- If no malfunction can be found:

- Flush refrigerant circuit with
compressed air and nitrogen.

- Repeat test.

Note:

- If operation is not OK after
refrigerant circuit has been
flushed, expansion valve must be
replaced.

Possible deviation from

specification

Possible cause

Corrective action

- High and low pressure normal at
first

- After some time, high pressure
increases above specification and
low pressure drops to value in
graph or below

- Required cooling output is no
longer attained.

- Expansion valve malfunctioning

- Moisture in refrigerant circuit

- Examine expansion valve for dirt
or corrosion; replace if necessary.

- Flush refrigerant circuit with
compressed air and nitrogen.

Note:

- Always replace receiver for this
malfunction.

Possible deviation from

specification

Possible cause

Corrective action

- High pressure normal or too high - Too much refrigerant in circuit

- Extract refrigerant from

Pressures, checking on vehicles

13/2/2005