I have a 2006 Audi A 6 with 4.2 and automatic has 27,000 miles, I have had many glitches with this car from gas gauge failure, keyless start failure, gps freezing up and not moving or the screen just goes black, lost of power sterring fluid tech told me it evaporates becuase of temp of engine so I laugh at that one and after several fill up they look and found a leak, now my a/c is malfuntion, have temp set at 72 on auto mode and with out any reason the driver far left Vent and rear Vents start Blowing EXTREME Hot Air, to the point of being so Hot that you can not touch the vent and to spin the wheel to turn it off you have to touch it several times that hot to a Touch, Example would be a water glass filled with fresh brewed coffee that hot I just pick up a themator to try and see how hot it is. It is sparatic in nature yesterday it happen several times today nothing so far, car was at audi for a week and I think I got a B S answer to trouble saying that Freon was down some, also I have had temp set at 72 and it got so cold that I have to crank up temp setting 78 to get some heat I like it cool I rarely complain about cold temps and when it does blow that extreme heat the front center vents go to much colder temp and passenger side far vent next to door goes to luke warm, also I want to get audi rep to in to talk too do you think that may help, I look for this A 6 to just short out and burn
The temp control system in those is fairly complicated. You might have a temp sensor out, that is why it changes temp, thinking it is giving what is asked for. I would definitly talk to the Audi rep and ask him if there are any Techs qualified to repair their HVAC system, because this dealer cant seem to do it. Be the squeeky wheel and you might get the grease, considering they have had your vehicle for repairs already.