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