Volkswagen Golf / Golf GTI / Jetta. Manual — part 1012

(see diagram)

- Required cooling output is not
attained.

- Compressor noise (particularly
after switch-on)

- Expansion valve or compressor
malfunctioning.

refrigerant circuit.

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

- Replace expansion valve.

- Re-charge refrigerant circuit.

- Repeat test.

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

- Re-charge refrigerant circuit.

- Repeat test.

Note:

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

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.

- A/C compressor malfunctioning. - Flush refrigerant circuit with

compressed air and nitrogen.

- Replace A/C compressor and
receiver.

Note:

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

Pressures, checking on vehicles

13/2/2005

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

Possible deviation from

specification

Possible cause

Corrective action

- High and low pressure normal

- Required cooling output is not
attained.

Too much
refrigerant in
circuit

- Discharge refrigerant circuit.

- Flush refrigerant circuit with
compressed air and nitrogen.

- High and low pressure normal

- Compressor noise (particularly
after switch-on)

- The required cooling level is
obtained.

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 (without
internally regulated
compressor), checking

Test requirements

- Radiator and condenser clean
(clean if necessary)

- Ribbed belt for A/C compressor
and generator is correctly
tensioned.

- All air ducts, covers and seals
OK and properly installed

- Flaps reach their end positions.

- Engine at normal operating
temperature

- Evaporator and heater not
drawing in secondary air at
maximum fresh-air blower speed.

Pressures, checking on vehicles

13/2/2005

Note the following points when
engine is running and A/C system
set to maximum cooling output:

- Fresh air blower running.

- Coolant fan in operation or is
switched on.

- Recirculating/fresh air door in
"recirculating air" position.

- Ambient temperature greater
than 15

0

C.

- A/C Evaporator Temperature
Switch E33 is correctly installed
and its switching temperatures are
OK.

Checking

- Switch ignition off.

- Connect pressure gauge set
(service station).

- Take pressure gauge reading.
Two results A and B can be
displayed.

Ambient temperature in degrees

Celsius

Pressure in refrigerant circuit in bar positive

pressure

+15 C

3.9

+20 C

4.7

+30 C

6.7

+40 C

9.1

- A- Pressure in refrigerant circuit
is lower than indicated in the table,
not enough refrigerant in circuit.

- Localize leak using leak detector.

- Pressure relief valve opened,
check activation for coolant fan
according to wiring diagram.

Check for constricted refrigerant
pipe and hose cross-sections
caused by inadequate bending
radii or external damage. If no
malfunction can be found, flush
refrigerant circuit.

Pressures, checking on vehicles

13/2/2005

- B- Pressure in refrigerant circuit
in line with table or higher:

- Start engine.

- Set air conditioning system to
maximum cooling output.

- Open doors.

- Open air vents in instrument
panel.

Engine drives A/C compressor by
ribbed belt via A/C Clutch.

Note:

- If A/C compressor is not being
driven, check voltage supply for
A/C Clutch N25 according to
wiring diagram.

- If voltage supply is OK, repair
A/C clutch.

If A/C compressor is driven, check
refrigerant circuit:

- Set engine speed to 2000 RPM.

- Observe pressure gauge set:

Specified values

High pressure side:

Increasing from pressure with
engine switched off up to
maximum 20 bar positive
pressure.

Low pressure side:

Decreasing from pressure with
engine switched off up to 1.3 bar
positive pressure.

Restrictor, reservoir and
A/C Compressor
Regulator Valve N280
(externally regulated
compressor), checking

Pressures, checking on vehicles

13/2/2005