A/C Signal: Testing and Inspection

AIR CONDITIONING COMPRESSOR SIGNAL, CHECKING

Special tools, testers and auxiliary items
- VAG 1551/1552 scan tool with VAG 1551/3 adapter cable
- VAG 1598/18 test box
- Multimeter (Fluke 83 or equivalent)
- Connector test kit VW 1594
- Wiring diagram

Check conditions
- Function of A/C OK
- A/C switched off
- Interior of vehicle is at room temperature, above 15 °C (59 °F)
- No malfunctions stored in Diagnostic Trouble Code (DTC) memory See checking DTC memory.

Test sequence
- Engine running at idle

- Connect VAG 1551/1552 scan tool and select "Engine Electronics" address word 01.

Indicated on display

Rapid data transfer HELP
Select function XX

- Press buttons -0- and -8- to select "Read Measuring Value Block" function 08 and press -Q- button to confirm input.

Indicated on display

Read Measuring Value Block HELP
Input display group number XXX

- Press buttons -0-, -0- and -8- for display group 008 and press -Q- button to confirm input.

Indicated on display (1 - 4 = Display fields)

Read Measuring Value Block 8 ->
1 2 3 4

- Switch on A/C (lowest temperature and highest blower speed).
- Check specifications for A/C (display fields 3 and 4)





NOTE: The A/C compressor will be switched off (Compr. OFF) when the ECM recognizes full load and the air conditioning is switched on (A/C-HIGH).

Continuation

If the display does not indicate as described:





- Connect VAG 1598/18 test box to ECM wiring harness.
- Check wiring between test box sockets 37 and 39 respectively and A/C for open circuit according to wiring diagram.

Resistance: maximum 1.5 Ohms

If the specification is not attained:
- Check wiring according to wiring diagram.