Volkswagen Golf / Golf GTI / Jetta. Manual — part 1013

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.

Repair Manual, Heating & Air

Conditioning, Repair Group 87 ,

Specified values:

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

Pressures, checking on vehicles

13/2/2005

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 is displayed in
measured value block

.

Repair Manual, , Repair Group

87,

- 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. 0.8 A (displayed in
measured value block)

Repair Manual, Heating & Air

Conditioning, Repair Group 87 ,

Pressures, checking on vehicles

13/2/2005

.

- 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,

- 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.

Note:

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

Pressures, checking on vehicles

13/2/2005

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

- A/C compressor malfunctioning.

- Check activation of
Compressor Regulator Valve
N280 .

- Flush refrigerant circuit with
compressed air and nitrogen.

- Replace compressor.

- High pressure increases above
specification

- Low pressure only drops slightly,

- Required cooling output is not
attained.

- Constriction or obstruction in
refrigerant circuit

- 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

- If no malfunction can be found:

- Flush refrigerant circuit with
compressed air and nitrogen.

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

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

- Required cooling output is no
longer attained.

- Moisture in refrigerant circuit

- Flush refrigerant circuit with
compressed air and nitrogen.

- High pressure normal,

- Low pressure too low (see
graph),

- The required cooling level is
obtained.

- Activation of A/C Compressor
Regulator Valve N280
malfunctioning

- A/C compressor malfunctioning.

- Check activation of
Compressor Regulator Valve
N280 .

- Flush refrigerant circuit with
compressed air and nitrogen.

- Replace compressor.

Note:

- For the malfunction "high
pressure normal, low pressure too

Pressures, checking on vehicles

13/2/2005