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With Manufacturer's Scan Tool



Signal From/To Air Conditioning System, Checking

Special tools and equipment
- V.A.G1551 scan tool or V.A.G1552 mobile scan tool with V.A.G1551/3B cable
- V.A.G1598/31 test box
- V.A.G1526 or Fluke 83 multimeter
- V.A.G1594 adapter set
- Wiring diagram

Test conditions
- Air conditioner functioning OK.
- Air conditioner must be switched off
- No codes must be stored in DTC memory, Check DTC Memory.
- Vehicle at room temperature (warmer than + 15 degrees C).

Test sequence
- Connect V.A.G1551 scan tool (V.A.G1552). Start engine and select "Address word" 01 of engine control module. Engine must be running at idling speed. (Connecting scan tool and selecting engine control module. [1][2][3]Connecting VAG 1551 Scan Tool)

Indicated on display

Rapid data transfer HELP
Select function XX

- Press keys 0 and 8 for function "Read measured value block" and confirm entry with Q key.

Indicated on display

Read measured value block HELP
Input display group number XXX

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

Indicated on display: (1 to 4 = Display zones)

Read measured value block 50
1 2 3 4

- Observe display in display zone 4. It must show Compr. OFF.
- Switch on air conditioning system.
- Select lowest temperature and highest blower speed.

The display in display zone 4 must change to Compr. ON.

- Floor accelerator pedal quickly and then release (brief burst of throttle).

The 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 -> key.
- Press keys 0 and 6 for "End output" function and confirm input with Q key.
- Switch ignition off.

If the display does not change:







- Connect V.A.G1598/31 test box to control module wiring harness. Engine control module remains disconnected.
- Check wiring for open circuit between test box sockets 40 + 41 and air conditioner system using wiring diagram.
Wire resistance: max. 1.5 Ohms

If no fault can be found in the wiring:
- 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 engine control module was disconnected from permanent positive, readiness code must be generated again.
Monitors, Trips, Drive Cycles and Readiness Codes
Monitors, Trips, Drive Cycles and Readiness Codes
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