Happens in my car now
At first I thought it could be anything and almost certainly linked with the very sharp changes in temperature we've been having. All the snow brought into the car by feet over the winter, getting into the carpets and underlay, evaporating during the day. But as soon as the sun goes down the temperature turns cold very quickly, evaporate is trapped and is cooled qickly and just condenses on the glass. I thought it could be that I was leaving the climate control on and just shutting the car off, allowing any moisture in the AC unit to come up through the vents. I even thought that it could be my sport. Swimming. Getting out of a hot swimming pool with wet hair, wet kit and getting straight into a ice cold car for a short trip home was putting a lot of moisture into the air of the cabin, which then condenses on the windows. Though it usually does this immediately, especially a car full of swimmers....3 - 2 - 1 - cant see.
But, I have driven the car for a while now, with full temp blasting into the foot wells and venting all the air out of the cabin before shutting off, its bone dry in there now. It still does it and some times its seriously bad, not just a frosty mist on the windscreen, but full on beads of water, like it had been raining inside the car*. The dash and the steering wheel also had condensate on them as well as the rear window (but not the side windows?!). The problem, I'm almost certain now is that there is a leak. Quick look on Skoda forums reveals a fault with my cars Pollen filter seal. In fact it doesn't just affect my car, it affects the VW Passat its based on too (B5.5) and I've seen the official fix letter from VW confirming the problem. The seal around pollen filter rots and lets water in, this water then ends up in the passenger foot well and later under the passenger seat where the ECU is. Around the pollen filters air box there are also bungs to let water drain away, these can get blocked over time with dead leaves and other crud and eventually your pollen filter drowns in water. Removing the bungs completely solves that problem, but might let fumes into the cabin. The fix for the pollen filter seal is simply a new lining of mastic tape (that closed cell foam stuff) and a application of bathroom sealant.
so yeah, try using the heater, exchanging interior air with outside air before parking up (provided the conditions are ok) and turn off/close vents on the climate control before shutting off to trap any moisture in the AC system. If it still does it then it may well be a leak, like mine.
so at the weekend Ill be doing this:
http://briskoda.net/forums/blog/18/entry-62-superb-mki-water-ingress-cure/
* Full blast heater did not cure this, even after an hour of driving with 30 deg air coming out the vents I still had water everywhere. The only way I could even get going was to fetch a beach towel and mop the windscreen with it!!
