On the April 11 show, the caller said the film was dry and also appeared in summer. I think it is like a smoke film. I have something similar on my 93 LeSabre and I wash it off regularly. It’s like something in the HVAC is vaporizing or decaying. No real smell is there.
The off-gassing of interior plastics, combined with pollutants in the air, create a film. It can be difficult to remove, but it will come off.
A leaking heater core will put an oily film on the windows which is more difficult to remove. You can usually smell antifreeze if the heater core is leaking.
Smoking in the car will also deposit a film on the windows and everything else.
I’m surprised that your 1993 dash board is still outgassing so much that you have to clean it. What do you use to remove the film?
It turns out I have been cleaning off the white film from various anti-fog remedies I had been applying. Here in Vancouver Canada (on the ‘wet’ coast) it goes from wet to dry every week. I have yet to find an antifog that doesn’t leave streaks when dry.
The best thing I have found to remove this film is crumpled up, dry newspaper. Just scrub it, hard.
Do you use Armor All or some such similar product?? These products have a tendency to off-gas once applied. It’s almost impossible to keep your windows clean when you use this junk.