A/C refrigerant system, testing: Notes

WARNING: This page does not describe the selected car, but rather 17 other vehicles, including the 2009 Audi S4, 2009 Audi A4, 2008 Audi S4, 2008 Audi RS 4, and 2008 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.

Special tools and equipment

Diagnostic Operation System VAS 5051A e.g. with Diagnostic Cable - 3 Meter VAS 5051/5A and K-Lead Adapter Vas6017B VAS 6017B (or K-Lead Adapter VAS 6017A)
Minitester V.A.G 1362 (for temperature measurement) or commercially available thermometer

Test requirements

Ambient temperature above 15 °C
Radiator and condenser clean (clean if necessary)
Ribbed belt for compressor drive OK and correctly tensioned, pulley actually driving compressor (not for vehicles with 8-cyl. engine)
Compressor drive unit (connection between compressor and engine) properly installed (vehicles with 8-cyl. engine only → Vehicles with 8 cyl. engine (compressor drive via a shaft) )

All air guides, covers and seals OK and properly installed
Air flow through dust and pollen filter not impeded by contamination
Vehicle not exposed to sunlight
Engine warm

DTC memory checked → Diagnostic Trouble Code (DTC) Memory, checking (function 02) , all displayed faults eliminated and DTC memory erased → Diagnostic Trouble Code (DTC) Memory, erasing (function 05)
Coding checked and corrected if necessary → Climatronic Control Module J255, coding (function 07) and reading measuring value block → Read Measuring Value Block (function 08)
Basic setting performed → Basic Setting (function 04)
All instrument panel vents open

Hood closed
Settings on operating and display module, Climatronic Control Module J255 :

"Auto" mode
"LO" temperature setting (for drivers and passengers side)
Compressor on (lamp in ECON button not lit)

Functions with engine running (and air conditioner switched on):

Operation of Coolant Fan V7 (speed governed by pressure in refrigerant circuit and engine temperature)
Operation of Fresh Air Blower V2 at maximum speed
Switching of air conditioner to recirculated-air mode (approx. 1 minute after starting vehicle, fresh-air/air flow flaps are closed and recirculated-air flap opened, air is drawn in by Fresh Air Blower V2 from passengers footwell)

NOTE:

If one of these test requirements is not fulfilled, check DTC memory → Diagnostic Trouble Code (DTC) Memory, checking (function 02) and perform Output Diagnostic Test Mode (DTM) diagnosis → Output Diagnostic Test Mode (DTM) (function 03) .