slpm0923

I'm absolutely baffled!!! I have a 1990 Audi 100, bought it a couple years ago and haven't had many major problems with it. I do have one problem and it's more aggravating than anything. I generally warm the car up for about five or ten minutes before I go anywhere. Once I do head out about ten minutes into the ride my windows are completely fogged up with the exception of a small area in the windshield. This also only occurs during winter months when the temperature is below forty degrees or so. I've played around with the climate control attempting to fix the problem but I've not had any luck. I just replaced the thermostat (it hasn't worked since I bought the vehicle in November of 2005) thinking that was the answer to my problem, but apparently it goes deeper than that. I've looked through hundreds of threads looking for someone who may have had a similar problem and couldn't find a one. Does anybody have any suggestions they would like to share with me on how I may fix this aggravating problem. Thanks in advance for any time spent helping me. Sean

DaveInSaltLake

Your problem may stem from several faults. If the drains in the plenum are clogged you may be getting water draining into the interior. If it's severe enough your carpeting may even be wet. Another potential cause of moisture inside the passenger compartment could be a leaking heater core.

Another possible cause could be the failure of the servo motor that moves the flap that directs air toward the defrost position. On the C4s it's a nasty job to get to them. Hope your car is a bit easier if that's your problem.<ul><li><a href="https://forums.audiworld.com/v8/">https://forums.audiworld.com/v8/</a</li></ul>

4Driver4

Broken spring on re-circ door. Ask on the 100/200/5000 forum.

rmccomiskie

Had the same problem on my 1990 200 Quattro. What's happening is there's a spring on the flap that holds it closed, i.e. non-recirc mode. When the spring fails, the flap goes into permanent recirc mode that allows no fresh air into the car. The moisture builds up and collects on the cold windows.

Pull the panel under and behind the glove box. Should be held on with a few phillips screws. Wiggle into the passenger footwell head first. Look up behind the glove box. You should see the recirc flap and a nearby vacuum actuator. There's supposed to be a spring joining the two. Mine was missing entirely. I bought a 4 inch spring at Home Depot and bent the ends to fit. Cheap and easy fix. Should take about an hour.