Condensation in cab
 

My cab is getting really wet inside on the roof and windshield. The door seals are new and I checked they’re sealing properly and there’s no leaks, carpet is dry everywhere, but somehow moisture is getting in, there is so much condensation on the roof, it gets really wet, I have to towel it off.

Anyone have any experience with this? I was told by a mechanic to put dynamat on the roof and it will stop, but that sounds odd to me.

Re: Condensation in cab
 

I'm assuming by your handle that you have a '71 C20. How is the driprail seal? Is it all chipped out and rusted?

I live in western WA and know how wet it can be, and we've had a LOT of rain lately.

Gary

Re: Condensation in cab
 

Do you have leaves blocking the cowl drain holes under the vents?

Also check the bottom of the windshield, the cowl area, and the firewall for rust.

Re: Condensation in cab
 

Generally speaking indicates a heater core issue, even in modern vehicles.

Re: Condensation in cab
 

Oh, and do you have clearance lights on the roof?

Gary

Re: Condensation in cab
 

Good starting point...71 C20 CS, does it smell or even give you that "taste" of anti-freeze when you drive it?

Re: Condensation in cab
 

The drip rail is in good shape, no rust on the roof.

Re: Condensation in cab
 

I don’t think it’s the heater core, no coolant smell or leaks, the cab seems tight I don’t understand where it comes from. Even with a waterproof cover and tarp over it condensation still builds up.

Re: Condensation in cab
 

Cowl is free of debris.

Re: Condensation in cab
 

Are the Fresh air vents opened or closed?

Do they have debris or leaves in them?