With Manufacturer's Scan Tool

Signal From/to Air Conditioning, Checking

Special tools, test equipment and auxiliary items
- VAG 1551 scan tool or VAG 1552 mobile scan tool with VAG 1551/3B cable
- VAG 1598/31 test box
- VAG 1526 hand multimeter or VAG 1715 multimeter
- VAG 1594 adapter set
- Electrical Wiring Diagram

Test conditions






- All fuses must be OK
- Battery voltage must be at least 11.5 V
- Air conditioner functioning OK
- Air conditioner must be switched off
- All electrical accessories, e.g. lights and rear window defroster must be switched off
- No DTCs must be stored in DTC memory.
- Vehicle at room temperature (warmer than +15°C)

Test sequence
- Connect VAG 1551 scan tool ((VAG 1552). Start engine and select "Address word" 01 of Motronic Engine Control Module (ECM) -J220-. Engine must be running at idle speed.

Indicated on display

Rapid data transfer HELP
Select function XX

- Press buttons -0- and -8- for function "Read measuring value block" and confirm entry with -Q- button.

Indicated on display

Read measuring value block
Input display group number XXX

- Press buttons -0-, -5- and -0- for "Display group number 50" and confirm entry with -Q- button.

Indicated on display (1 to 4 = Display zones)

Read measuring value block 50 ->
1 2 3 4

- Check specifications for air conditioner (display zones 3 and 4)






- Observe display in display zone 4. It must show: Compr. OFF.
- Switch on air conditioning system.

- Select lowest temperature and highest blower speed.
Display in display zone 4 must change to Compr. ON.

- Floor accelerator pedal quickly and then release (brief burst of throttle).
Display in display zone 4 must change from Compr.ON to Compr. OFF for a few seconds (compressor switch-off when vehicle is accelerating).

- Press -> button.
- Press buttons -0- and -6- for "End output" function and confirm input with -Q- button.
- Switch off ignition.

Continuation

If the display does not change:
- Remove inner plenum chamber cover at left.






- Connect VAG 1598/31 test box to control module wiring harness. Motronic Engine Control Module (ECM) -J220- is not connected by this action.
- Check wiring for open circuit between test box sockets 40 + 41 and air conditioner system using Electrical Wiring Diagram.
Wire resistance: max. 1.5 Ohms

If no wiring malfunctions can be found:
- Check function of air conditioner control module.
- Check DTC Memory, if necessary, repair any malfunctions and then Erase DTC Memory.
- Read readiness code. If DTC memory has been erased or Motronic Engine Control Module (ECM) -J220- was disconnected from battery positive, readiness code must be generated again.