Hi all, I have a 1999 Ranger XLT 4x4 4.0 . Now that the nights are getting cooler,foggier,wetter,( Pacific Northwest) my windshield is covered with ton's of moisture on the inside in the mornings. This is happening overnight before I start the truck and turn on the defroster. It's not antifreeze on the windshield as I've had leaking heater cores before and am quite familier with their symptoms. I'm 99.9% sure this is not the case. Is there a vent or a door of some kind not working properly that might be causing this to happen? Any insight or ideas would be much appreciated. Thanks

 

I would suspect there is a leak allowing water to get into the cab. It can be from the rear window seal, the windshield seal, or the sheet metal/plenum area. Most likely.
I would inspect the carpet or floor mat under the dash on both sides, and move the seat forward and inspect the rear under-seat area for moisture. If you find either wet, start looking for a leak.
The heater may have a re-circ setting, which would close a flap to the air intake inside the plenum at the base of the windshield. If you leave it on re-circ, you'd keep the air, mostly, that was there when you parked the truck. If the plenum is full of leaves or debris, it can hold water, that could spill over the lip of the air intake. Inspect through the slots near the wiper arm pivots for excessive crud. Older models had a couple inspection(?) plates that could be removed, along with the wiper motor, for access to clean out detritus. I pulled a gallon bucket of stuff out of mine once, so far. If stuff was left there for a long time, you could have a rusted through plenum floor, and that might allow water to flood your cab/rug.
I did have a sheet metal joing, vertical at that, which was not sealed at the factory and allowed water to trickle down under the passenger side floor and soak the pad. It took 4-5 days in the sun to dry out, and had lifted the paint from the floor. I used some RTV on the joint using a popsicle stick and it has stayed dry since. I used to get a very nice coating of water on the inside of the windshield before that repair. The leak was only visible by lying in the passenger seat, upside down, to look at the underside of the sheet metal forming the plenum.
tom

 

Get in the car, have some get a hose, and start running water around all the seals to the cab. Doors, windows, and what not. Carwash works good too. That will start your pinpointing.

 

Thank you for your responses, lots of good suggestions. I am sorry, I forgot to mention that the problem didn't start until we had the windshield replaced. After the problems started, we did have the glass replacement company check the seals on 3 separate occasions and they said there were no leaks found. Could they have damaged something else during the replacement? We have found no moisture on the floors and there is one specific spot on the windshield that seems to freeze over when it gets really cold. This is the most aggravating problem.

 

You get freezing in Seattle? Who knew.
Where does it freeze up? By the mirror where the defrost flow is interrupted? Or elsewhere?
Does the whole inside get covered with condensate when it's chilly and humid outside? Or is it just a specific section? The one indicates pretty severe influx of water somewhere, the other not so much.
tom

 

My ranger does the same thing when it's extremely humid during the night. I just assumed it was the humidity causing the windshield to "fog" up on the inside.

 

TomW,

There is condensation everywhere inside when there is high humidity outside and when it gets cold, we had ice on the inside. Can't find a leak anywhere. And the problem didn't start till we replaced the windshield. Last night, it was cold, but there was no humidity in the air, so the windshield was clear...can't figure this one out.

 

Unless you leave the window open, you should not get enough 'air exchanges' during the night to cause the inside windshield to be covered with condensation. There is just not enough H2O.
I would suggest checking under the floormat or carpet for dampness. I would also slide under the vehicle and look for a missing or holy body panel plug. There are a few ovalish plugs that can allow external splash to get into panels and humidify the cab if they are missing, loose, or punctured.
If you think the replacement windshield seal is defective, test with a garden hose. If it leaked, you'd have water on or under the carpet and a soggy pad. When my cab had the leak, it was barely exposed to rain, hard to see, but it got the pad totally soaked, and would fog up the inside windshield whenever the temperature was 'just so'. I finally laid upside down and looked, after removing the glove box, I think, and was able to see corrosion where the leak occurred. You must have external water to get that much on the windshield.
tom