A8 2001 V8 40V Heater and overheating problems
 

Hi Guys,


New member to this forum but reading it for 2 years already.
Own a 2001 A8 4.2. Started having heater problems last winter (i live in Canada). Even when engine gets to normal temp (90 Celsius), very little heat comes out from all the vents, whether i choose 21 or go all the way to HI.
Middle dash vent stays cold no matter what. Only after driving the car for about 15-20mn do i start having some real heat. Also, it is warmer on the passenger side that the driver side. Adjusting the climate control doesn't change anything anymore. Used to work last year but not anymore...


In summer, to get cool air, i need to go all the way to LO. As soon as I go 19-20 Celsius, i get hot air. The cool air is really cool, no problem with AC compressor.
Any ideas ? Several people on the forum have some of my problems but no one seems to be having the exact same one.


I do not seem to have any obvious leak, since a good friend of mine does some of the maintenance on the car and is extremely thorough when he inspects the car.


I also get random engine overheating, whether in hot traffic with or without AC or at highway speed (and yes, the Aux fan works and the belt driven main fan also works fine). Driving in second or third gear at higher RPM does eventually get the temp down. Sometimes, no problems, sometimes yes... It overheats more in hot weather... On the other hand, i can let the car running on my driveway at idle for 30mn, with AC on and no overheating... I am at a loss, no logic there...
I Had the AC condenser remove from the radiator, Professionally cleaned both of them to eliminate the dust film in between. That was the first step. Any ideas for the next step ? I am a Do It Yourself guy but do not mess around with THIS car. I always take it to professionals. The main problem is that it seems that very few mechanic have good knowledge of HVAC issues on Audi cars... I do not even trust Audi Dealership, on top of being way too expensive for the quality of work that they provide (and i know what i am talking about, as I saw them many time giving work to be done on my now 15 years old car to a 23 years old mechanic knowing only how to interpret a Vagcom reading and being at a complete loss when the readings return no error codes but being faced with an obvious problem...!!!)
Loss of my time and getting the feeling that they are openly stealing my money...


Thank you for the help.