Volkswagen Golf / Golf GTI / Jetta. Manual — part 1014

low" , note the following: If
malfunctioning, evaporator may
ice-up or cooling output is not
reached.

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

- Check measured values of
Evaporator Vent Temperature
Sensor G263 .

- Check activation of A/C
Compressor Regulator Valve
N280

Repair Manual, Heating & Air

Conditioning, Repair Group 87 ,

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
attained.

- Too much refrigerant in circuit

- Extract refrigerant from
refrigerant circuit.

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

- Replace A/C compressor.

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

- Re-charge refrigerant circuit.

- Repeat test.

- 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.

Pressures, checking on vehicles

13/2/2005

Note:

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

Expansion valve, receiver
and A/C Compressor
Regulator Valve N280
(externally 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 of
service station.

Note:

- Switching pressures for actuation
of A/C Compressor Regulator
Valve N280 and Coolant Fan V7
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 ,

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 20
bar.

Low pressure side:

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

A - Low pressure (measured at
service connection) in bar
absolute

B - Control current for A/C
Compressor Regulator Valve
N280

C - Permissible tolerance range.

Note:

- Under unfavorable conditions
(very high ambient temperatures,
high humidity), pressure on high-
pressure side may increase to
max. 29 bar.

- Control current - B - is displayed
in measured value block.

- High pressure measured by High
Pressure Sensor G65 is displayed
in measured value block

.

Repair Manual, Heating & Air

Conditioning, Repair Group 87 ,

Pressures, checking on vehicles

13/2/2005

- Low pressure settles as a
function of control current for A/C
Compressor Regulator Valve
N280 within compressor output
range in tolerance range.

- Under unfavorable conditions
(very high ambient temperatures,
high humidity), compressor output
may not always be sufficient to
attain the specified value.

- The specified operating current
for the regulating valve must be
greater than 0.3 A in order to
ensure reliable valve actuation.

- In the setting "maximum cooling
output" control current is regulated
to approx. 0.65 A up to 0.85 A
(vehicle specific, displayed in
measured value block)

.

Repair Manual, Heating & Air

Conditioning, Repair Group 87 ,

- At absolute pressure, 0 bar
corresponds to absolute vacuum.
Normal ambient pressure equals 1
bar absolute pressure. 0 pressure
corresponds to an absolute
pressure of one bar on most
pressure gauges (indicated by -1
bar below 0).

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.

- Activation of A/C Compressor
Regulator Valve N280
malfunctioning

- Not enough refrigerant in
refrigerant circuit.

- Check activation of
Compressor Regulator Valve
N280 .

- Localize leak using leak detector
and eliminate.

- Re-charge refrigerant circuit.

- High pressure normal.

Pressures, checking on vehicles

13/2/2005