Signal From/to Air Conditioning, Checking

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, Checking and Erasing 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. Connecting scan tool and selecting Motronic Engine Control Module (ECM) -J220-.

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, Checking and Erasing 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.