Audi Workshop Service and Repair Manuals

Test requirements for vehicles with air-conditioners

• ● Vehicle at room temperature (warmer than + 15 °C)
• ● Air conditioner switched on
• ● Lowest temperature and fastest fan speed selected

The final control diagnosis activates the following components in the stated order:

1. Injection start valve (N108)

2. Valve for exhaust gas recirculation (N18)

3. Air conditioner compressor cut-in

4. Fuel cut-off valve (N109)

5. Solenoid valve for boost pressure limitation (N75)

6. Glow plug relay (J52)

7. Pre-glow time warning lamp (K29)

8. Low heating output relay (J359)

• only in vehicles with manual gearboxes

9. High heating output relay (J360)

• only in vehicles with manual gearboxes

10. Blower relay (J323)

• only for engine code AHF

• ‒ Connect fault reader V.A.G 1551 (V.A.G 1552) and select the engine electronics control unit using "Address word" 01. For this purpose the engine must be running at idling speed.
  (Connecting fault reader and selecting engine electronics control unit .)

• ‒ Press keys 0 and 3 for "Final control diagnosis" function

• ‒ Confirm input with Q key.

• Valve actuation has a considerable effect on combustion noise (pre ignition).

If no change in the combustion noise is heard:

• ‒ Check the injection timing control range
  => Page 23-59
• ‒ Press the ⇒key.

• The injector valve should click.

Notes:

• ◆ Due to the engine noise, the clicking of the valve is not audible and therefore may only be detected by feel.
• ◆ The piston movement of the mechanical exhaust gas recirculation valve is clearly visible in the side slot.

If the injector does not click:

• ‒ Test EGR valve => Page 23-68
• ‒ Press the ⇒key.

• Check the air conditioner compressor shutoff.
• This test step is also invoked for vehicles without air conditioners.

• The air conditioning conditioner compressor must stop within 5 secs. (visual check), and then start approx. every 5 secs. and then stop again.

If the conditioner compressor is not switched off:

• ‒ Checking the air conditioner compressor shutoff
  => Page 23-101
• ‒ Press the ⇒key.

• The engine must stop.

If the engine does not stop:

• ‒ Switch ignition off.
• ‒ Unscrew the fuel cut-off valve and remove any metallic parts or dirt
• ‒ Repeat final control diagnosis and if the engine will still not stop, replace the fuel cut off valve.
• ‒ Press the ⇒key.

• The solenoid valve must click.

Note:

The clicking of the valve is difficult to hear and is therefore best checked by touch.

If the solenoid valve does not click:

• ‒ Test boost pressure control solenoid valve
  => Page 23-50
• ‒ Press the ⇒key.

• The relay must click.
• Due to the high current consumption, the switching on and off of the relay may also be observed from the interior light becoming brighter and darker.

If the relay does not click:

• ‒ Check the glow plug relay:

=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations

• ‒ Press the ⇒key.

• The warning lamp must blink.

Warning lamp does not blink:

• ‒ Check preglow warning lamp => Page 28-4
• ‒ Press the ⇒key.

• The relay must click.

If the relay does not click:

• ‒ Test low heating output relay:

=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations

• ‒ Press the ⇒key.

• The relay must click.

If the relay does not click:

• ‒ Test high heating output relay

=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations

→ Fitting location Relay box on bulkhead

-1- Low heating output relay
-2- High heating output relay

• ‒ Press the ⇒key.

Only for engine code AHF

• Radiator fan must come on every 5 seconds and then stop again

If the radiator fan does not start:

• ‒ Check radiator fan actuation
  => Page 23-116.

Note:

The radiator fan may also be activated by the thermoswitch, the automatic gearbox or the air conditioner. When performing the final control diagnosis, ensure that the fan has not been activated for this reason.

• ‒ If necessary, allow engine to cool down.

• ‒ Press keys 0 and 6 for the "End output" function and press the Q key to confirm entry.