Any idea why my windows will fog up using the heat and switching to recirculate(takes a couple of minutes),switch back to fresh and it clears up.I like the recirulate cause it seems to blow a lot hotter.I have 1 a 92 p.u. with no a/c if that makes a difference.

 

Your air inside is humid due to you breathing and from snow or water on your shoes. A remote reason could be a leak in a window or something, but mine does the same when I have a puddle from the snow or water in my floor mats.

Erich

 

Yup. Both of mine do it too. You can prevent it by cracking a window a little bit.

 

I also own an 86 and it never does it, so I was thinking something might be wrong with the 92.

 

If you are super worried you could check out your heater core, make sure your floor isn't wet around it. You could also park in the garage to make sure water isn't leaking in from a window. It could be that your heater in the 92 is better so it evaporates more water from inside then you see more condensing on your cold windows.

Erich

 

A/C makes a huge difference. If you had A/C you could use recirculate because the coil condensates and pulls the moisture out of the cab. Your 86 may be the one which isn't working right. If the damper which switches outside/inside isn't closing all the way you may be circulating some fresh, dry outside air when on recirculate causing your windows to not fog. The same effect as cracking your window.

Just my $.02