I am having a problem with my 07 Jetta. The windows keep fogging up when the A/C is not running. The easy solution is to run the A/C all the time which is what the dealer suggested.The problem is that when the outside temp falls below 38 degrees, the A/C automatically shuts off and the windows fogg up to the point where you can't see. The dealer recently checked the entire system for leaks and suggested closing the vent on top of the dashboard which I did. This did not work. Any suggestions?

 

If you have a sunroof have the drains cleaned might be plugged and you have water in the car...

 

You may need to drain the vent system. In my 97 jetta, there is a flap on the firewall inside of the engine compartment under some insulation. there is a u shaped cut out that can be peeled back. then just lift up the flap, if there is water in there, you'll know immediately.

 

I also have similar problem to my 01 VR6. On snowy days my floor mat collects plenty of snow from my boots and now the interior becomes foggy easily, may want to find this vent/water thing. A temp solution is to use paper towels absorb the water inside of the glass, worked for me for a week or so before the fog comes back.