Audi Workshop Service and Repair Manuals

Notes:

• ◆ The air conditioning compressor signal informs the engine control unit that the compressor will be switched on in 140 ms.
• ◆ The engine control unit can send a signal via the same wire to shut off the air conditioner compressor.
• ◆ The engine control unit will shut off the air conditioning compressor in the following cases:
• ‒ During powerful acceleration (full throttle in first gear)
• ‒ In the emergency program (emergency running mode)
• ‒ After initiating of basic setting (Function 04)

Test requirements:

• ● Air conditioning system OK
• ● No faults stored in fault memory of engine control unit
• ● Vehicle at ambient temperature (warmer than + 15 °C)

Test sequence

• ‒ Connect vehicle diagnostic, testing and information system VAS 5051 and select vehicle system "01 -Engine electronics" in the selection. For this purpose, the engine must be running at idling speed.

→ Display on VAS 5051:

• ‒ Under -1- select the diagnostic function "08 - Read measured value block".

→ Display on VAS 5051:

•     1 -    Enter display group
  max. input value = 255

• ‒ Enter "050" for "display group number 050" in zone -2- and confirm the entry by pressing the Q key.

→ Display on VAS 5051:

• ‒ Switch off air conditioner.
• ‒ Specified value in display zone -4-: Compr. OFF
• ‒ Switch on air conditioning with "auto" button and set air conditioning to maximum cooling/heating. The compressor must run.
• ‒ Specified value in display zone -4-: Compr. ON
• ‒ Fully depress accelerator pedal suddenly and release again (brief burst of throttle).

→ Display on VAS 5051:

• ‒ Specification in display zone -4-: Display switches for several seconds from "Compr. ON" to "Compr. OFF" (compressor shut-off on vehicle acceleration)

If the readout in display zone is not as described:

• ‒ Connect test box V.A.G 1598/31 to wiring harness for engine control unit; do not connect the engine control unit => Page 24-19.
• ‒ Check for open circuit and short to positive or earth in the following wiring connections:

• ‒ Rectify any open/short circuit as necessary.
• ‒ If there are no faults in the wiring, check the operation of air conditioning.

=> Heating, Air Conditioner; Repair group 01; Self-diagnosis for air conditioner