I have searched and searched on here but can't find an answer to this one. I have no leaks in my truck and the heater core appears to be fine (ie: no smell in cabin).

When I get in my truck the windows are clear, it's when I start the truck that it instantly fogs up all the windows. I need to let it idle for 5-10 minutes with ac on and defrost/fresh air full blast to get it kind of able to see out of. It is as if the system is blowing the moisture in.

Has anyone dealt with this before? The first 3 winters with the truck were no problem. Last winter and this fall already, terrible.

Thanks,
Nate

I find cleaning the window really helps. I noticed this on my car when I was riding shotgun with my Son driving. I took a napkin and scrubbed my side pretty well.

Last week, my wife says to me "my car window fogs up so bad I cant see"

She went on to say "... and the odd part is that the passenger side was clear!" :o:

X2

check the a/c drain line. It's somewhere under the battery, don't remember the exact location. If it is clogged then the residual water will evaporate when the heat is turned on and fog the windows.

check the a/c drain line. It's somewhere under the battery, don't remember the exact location. If it is clogged then the residual water will evaporate when the heat is turned on and fog the windows.
I'll second that emotion. The drain for the HVAC is partially or completely restricted. On the firewall, just behind the passenger side exhaust manifold.

Coat hanger, piece of wire, or any other wire-like instrument that'll go in 2-3 inches and can be jabbed in and out.

Thanks. I bought some aerosol invisible glass that I saw on here was recomended. I will give that a shot. I will try the AC line tomorrow too. I will let you all know how it goes. Thanks again.

Ensure the recirculate air button is off. If not all the moisture is trapped inside the cab and then condenses on the cold windows.

Ensure the recirculate air button is off. If not all the moisture is trapped inside the cab and then condenses on the cold windows.

The moisture is trapped either way. The only way out for moisture, in either setting, is through the HVAC drain or the rear cab outdoor vents, or an open window.

Well the window cleaning lasted for a while, it is still a lot better. The AC drain is not plugged, and the fresh air button is always on, ac is on. I just put in one of those closet drier things to suck the moisture out too. I just don't get why the first few years I didn't have to deal with this. I did feel a cold draft under the passenger seat, but can't find where it is from. No moisture on the floor though. Hmmm?