Fogs up in winter

I have a 95 Aurora and am a tech. My Aurora has been fogging up when it is to cold for the ac compressor to come on. I thought I had a leaky heater core so I replaced it. When I removed the bottom cover it was dry as a bone, replaced it anyway. Thought I might have moister coming in through the fresh air intake so I blocked it off, same thing. I have talked with the tech's at the Olds dealer and they have not seen any such problem even checked with a local shop that specializes in AC and heater repair and they said they hadn't run into this problem either. i also checked all the sunroof drains to make sure no water was leaking into the passenger compartment that i might not easly see. If anyone could shed some light on this problem I would be delighted. This problem has been a thorn in my side for too long.
Please help
Carman999

open up the fresh air intake again, and also make sure that the air intake flap is open and not stuck closed. If the car can't get fresh air in the winter it will fog up.

I have had a 95 since 2001 and I have always had this same problem. Once the temp goes below 25 degrees or so it is impossible for me to keep the windows fog free. Especially if there is more than 1 person in the car.

My A/C works fine and i have had my heater core checked out. Cant figure out the problem.

Where exactly is the " frech air door flap" located? Sounds like a logical problem I should check out.

I'm kind of speaking generically here but I'll give you an example. VW Rabbits and Golfs had a fresh air pickup in the cowl area. several inches inside this entrance was a vacuum operated flap - if the flap were to stick shut it would never be letting fresh air into the car, thus recirculating the humid air causing the fog up condition. I'm not sure where it is on a Aurora, but in my Intrigue manual it shows like it would be just below where the cabin air filter is. The servo and vac lines that run it are inside the car. Looks like this stuff can be accessed by getting the glove box out, on the Intrigue.

The fresh air door flap is situated behind the instrument panel on the right.
It has an actuating motor that may have a blown fuse or jammed it shut.
FYI there is a recycle button near the A/C button on the dash.

The 95 Aurora's do not have a recirculate opption.
The recirculate door is behind the glove box, ECM,BCM and several other electronic modules. It is controlled by an electric actuator that screw onto the side of it. It didn't help my problem with it blocked open or shut I acctually think that there is a problem with water pooling inside the case possibly in the evaporator housing. If I don't run the AC compressor it will eventually stop foging. like one day of use without compressor functioning. I think is was probably a design flaw that was corrected in the following year model.
Carman999

The fresh air door flap is situated behind the instrument panel on the right.
It has an actuating motor that may have a blown fuse or jammed it shut.
FYI there is a recycle button near the A/C button on the dash.

Opps sorry, I was quoting from a 1996 manual

O.K. straw clutching time. Doesn't the A/C have a dryer for removing humidity or the evaporator housing have a drain to the outside of the car?
I have heard of some Auroras leaking at the windscreen wiper arm pivot. Maybe yours leaks when the snow melts.
I know that when my recycle door is shut the interior gets very misty.

weird, I had no idea the 95 had no recirculate button!
My dad has a 93 STS and it has no option for it, the car just decides if it wants it open or not, it's kinda lame, I would rather be able to tell it myself than have it try to guess the best approach all the time.