Hi I've been reading posts to see if anyone is having the same problem I am having. I own a 2001.5 1.8T A4. During the fall I took it in to resolve a heating problem. At that time the heat was not as hot as I expected. Sometimes it was ok, other times it was cool, not cold.
The dealer recommended a rad/heater core flush, which I did. When I got the car back the heat was working, still not HOT but better.
Last week in driving in -8C weather it went cold again and stayed there for a day or so, I called the dealer to try again. Befor I got to the dealer, it was OK again,not great but warm enough to slow the fan to 2 bars. (if you have one you know what I mean)
The dealer recommended a new heater core. I didn't think that was the problem because it sometimes works.
Questions:
1 Is there a heater control valve and if so, where is this? Have these been known to stick or be intermittent? is there a VAG code if it doesn't work?
2 Where is the motor that controls the damper that mixes hot and cold air? Again could this be the problem. Is there a code for this.


The dealer does not believe these are the problems, but cannot explain why the problem is intermittent.
BTW, the dealer implied that another flush "might" help because, since the coolent does not get changed on a regular basis, sludge builds up and can cause heater plugging. Is this like to oil sludge problem????
Thanks for any help or advice.
Barry in Toronto

 

Most likely, the heater core is still clogged. Either with coolant, some form of mineral deposits from using tap water to top off the coolant when it gets low, or I've recently heard that if you get oil into your coolant via either a bad headgasket or oil cooler, the oil will settle in the heater core causing clogging as well. The other possibility is that your thermostat is getting stuck closed; do you know when that was last changed? If not, add it to your list of things to try replacing, but lower on the list since its a pain in the *** to change. Doing a heater core reverse flush is pretty straight forward; there are a few writeups on here somewhere that you can follow. If it is indeed a clogged core, and reverse flushing it doesn't break the gunk out, you'll be up for a complete heater core replacement, which is as big, if not moreso, of a pain in the *** than the thermostat, so also put that on a last-resort-replacement.

Best of luck and welcome to the forums

 

I changed themostat at about 100,000km. Coolant was indeed cool. Now, coolant temp is solid on 90C according to the sensor I can "tune in on the radio".
I agree with you that there is some plugging since the collant has never been changed!
Also I once (maybe at 20,000) had an overfill when repairing one of my failed spark coils......
Do oyu think Audi should re think it's policy on not changing coolant?
Thanks
Barry