I have a '11 Ram 3500 4 door with a slider back window. Now that it's getting colder here, i notice a LOT of condensation on the inside of the windshield when i get in in the morning. Literally have to wipe it with a towel or the defrost would take forever. I don't remember near as much last year ?
Is it just from trapping the warm air in the truck when i get out, than it cooling overnight ? I've had plenty of old rigs that probably didn't seal as well, and none seemed to moisten the inside windshield as much. Is it due to the new "triple sealed" door weatherstripping they pimp in the advertising ?

Part 2 of question : Yesterday morning I sat in the truck for awhile with defroster on until it warmed up inside, than shut truck off . About an hour later went back to truck to take family to the store -- In the space between the rear door edges, and the slider window, but only high in the corners at the headliner, both sides were wet. Visibly wet, touch it and it was like wringing a sponge.

This morning it was gone. So today I sprayed the upper corners [and all over] of the rear window with a hose, and both rear doors for a few minutes, and...Nothing, no sign of a leak.
Is it just forcing the wet air to the upper back corners of the truck when the defrost is on ?

Any suggestions or similar experiences? I'm thinking of letting all the hot air out of the truck to equalize temps with the outside air each night, [ by opening the doors for a few minutes] --but this is often unpractical since i'm in Seattle area and half the time its raining.

The only other thing i can think is a got a "rock strike" star in the windshield a few months ago, about a 1/3" across, but you can't feel any blemish from the inside of windshield.
Thanks for your thoughts.

Yes, warmer moister air is what it's from. If you run the vents on full cold for a couple minutes to evacuate all of the warm moist air it will be a lot better. However if the cold air is also humid enough (due to the weather at the time) you're going to get condensation no matter what.

Thanks Secret Chimp, That's kind of what i figured. Just seems worse than i ever remember it being [ and in a newer vehicle than i'm used to driving ]. I am sort of baffled by the localized wet spots in the corners of the headliner.
Last two days out here were beautiful weather, as i'm sure they were across the Puget Sound as well !

If you run the HVAC system on Recirculate, whatever moisture is in the vehicle doesn't leave. Use the outside air setting.
Another trick to reduce interior humidity is to run the A/C even with a warm defroster setting, since A/C is a de-humidifier. In most vehicles, the Max A/C setting recirculates interior air; using that setting will not clear the humidity as well as fresh air.

Thanks Topside.
I have always used outside air and not recirc. I'll try engaging the A/C while in the defrost mode as you suggested.

You'd think i'd know this stuff after living in this wet NW climate for 20yrs... Seems like the older i get , the dumber i realize i am !

The headliner should not be wet, ever. What's happening there is water is seeking the lowest level and accumulating. Water is likely entering through somewhere above that level and the 1st thing that comes to mind is a sat-radio antenna on the roof, or roof seams, 3rd brake light, or a sunroof. Saw those problems many times when I ran a Dodge dealership bodyshop. Should be a warranty deal. Sometimes just dribbling water out of a cup locates the leak better than hitting it with hose pressure. The front of the headliner being wet indicates to me that water gets in from the roof, assuming truck is parked level when the water is getting in.

topside--- you were right about the water intrusion into the cab. I sent you a PM if you have a moment to read it. Thanks.

Not my first rodeo on that issue...PM'd ya back.