I bought ours second hand also. The first dealer I went to was not helpful at all. Found a different dealer and they were awesome, knew exactly what it was. It just took a bit to get the screen in.

good luck!

 

I have the same issue here especially when weather below 30F. Happened to my last two trips to Tahoe even with new windshield installed. I realized there is a gap with foam seal between the windshield lower edge and dashboard edge. It still leaking cold air in. Then I just bought a window sealing strip and cover that gap completely. On the way home the fogging issue was minimized. Hope my experience helps.