Vannin' Home Forums Ford How to... Fogged Windows

Hi all,
I took, or should I say I tried to, take my 77 E-250 (460 4 barrel), to work this morning, It was about 54 degrees and raining. A little on the humid side.
She started fine, and off we go. Turned on the defrost, and all that would come out is hot humid air. Had to keep wiping the windshield. Not once in awhile but constantly, non stop.
The blower was not drying the windows, but just coating them with fog, so I finally had to park it
What would cause this to happen? The van had AC at one time, but not now. There is plenty of air flow from the (windshield), vents.

Thanks for any input.

Hey Oh2me,

Welcome to the site!

Just spitballing here, but, heater core leaking? Airbox drain plugged? Water penetration into the airbox or ducts? Maybe the Ford guys have a better idea?

Bummer about the AC, sounds like it would surely help in your climate.

We know the defroster sucks, but will it do burnouts?

Working AC would definitely help this situation since the C system also functioned as an air dryer and de-humidifier. I have had multiple 75-91 Ford vans and none of them had any window fogging issues even though I live in western Washington where I get plenty of rain and it does get down to the teens in the winter.

You most likely have a failed firewall seal or weatherstrippping seal that is letting in too much moisture. As has been mentioned, a failing heater core can also cause the windshield to fog up. You want to get that looked at because having a heater core failure while you are driving is not fun at all. I had it happen to me in my 89 Ford van earlier this year. Pretty amazing smoke show in the cab.

Welcome to the site Oh2me ...