Checking air-conditioner compressor signal and air-conditioner compressor shutoff — AUDI

Special tools and workshop equipment required

V.A.G 1526 A
V.A.G 1527 B
V.A.G 1594 A
V.A.G 1598 A
V.A.G 1598/11
VAS 5051 with VAS 5051/1 and
VAS 5051/2

or

V.A.G 1551 with V.A.G 1551/1

Checking air-conditioner compressor signal

Note:

The signal from the air conditioner increases the pilot control value for idling-speed stabilisation to keep idling-speed stabilisation in control mid-range.

Reading measured value block 4
⇒
1
2
3
4
Read measured value block, Display group 004, engine idling
=>Page
01-103
.
Check display in zone 4.
Specification: 0XX X

Note:

Switching inputs at locations marked "X" can be ignored for test purposes.

Switch on air conditioner.
Specification: 1XX X

If display is not as described:

With ignition switched off, use adapter V.A.G 1598/11 to connect test box V.A.G 1598 A to connector C and also to engine control unit=>Page
24-13
.
Connect up voltage tester V.A.G 1527 B as follows.

Test box V.A.G 1598 A / Socket · Measure to
11 · Engine earth

Switch on ignition.
Switch on air conditioner.
LED must light

If LED does not light:

Pull adapter V.A.G 1598/11 off engine control unit position C.

If LED now lights:

Replace engine control unit => Page
24-16
.

If LED still does not light:

Check for open circuit and short to earth/positive in the following wiring.

Test box / V.A.G 1598 A / Socket · Air-conditioner switch -E30 / / Contact
11 · => "Current Flow Diagrams, Electrical Fault-finding and Fitting Locations" binder

If there is no fault in the wiring, check operation of air conditioner.

=> Heating, Air Conditioner; Repair Group 87; Air Conditioner; Servicing components of manually controlled air conditioner
Heating, Air Conditioner
Air Conditioner
Servicing components of manually controlled air conditioner

Checking air-conditioner compressor shutoff

Notes:

On accelerating from a standstill/low vehicle speed, air-conditioner compressor is switched off for approx. 12 seconds by engine control unit. If accelerator pedal is released sooner, time decreases to min. 3 seconds.
Air-conditioner compressor is also shut off by engine control unit after starting function 04 "Basic setting".

Test requirements:

No faults stored in fault memory
Engine idling
Vehicle at ambient temperature (more than +15 °C)
Air conditioner OK

Test sequence

Switch on air conditioner.
System in basic setting 4
⇒
1
2
3
4
Start basic setting, Display group 004, engine idling=>Page
01-73
.
Air-conditioner compressor must come to a halt (visual inspection)

If air-conditioner compressor is not shut off:

Switch off air conditioner and leave engine idling.
Enter "8" to switch to "Reading measured value block" function.

Reading measured value block 4
⇒
1
2
3
4
Indicated on display:

Check display in zone 4.
Specification: X0X X

Note:

Switching inputs at locations marked "X" can be ignored for test purposes.

Switch on air conditioner.
Specification: X1X X

If display is not as described:

With ignition switched off, use adapter V.A.G 1598/11 to connect test box V.A.G 1598 A to connector C of engine control unit only (not to control unit) => Page
24-13
.

Check for open circuit and short to earth/positive in the following wiring.

Test box / V.A.G 1598 A / Socket · Magnetic coupling / control unit -J153 / Contact
10 · => "Current Flow Diagrams, Electrical Fault-finding and Fitting Locations" binder

If there is no fault in the wiring, check operation of air conditioner.

=> Heating, Air Conditioner; Repair Group 87; Air Conditioner; Servicing components of manually controlled air conditioner
Heating, Air Conditioner
Air Conditioner
Servicing components of manually controlled air conditioner

If both air conditioner and wiring OK:

Replace engine control unit => Page
24-16
.