2nd Gen Non-Engine/Transmission defrost

[lumberjack98]

does anyone know why the defroster would make the windows fog up when on? only after about 20 minutes of driving does it seem to go away. before that it seems to better then worse at will and i have checked the water not low or dripping the heater box dosen't have leaves or anything in it (cleaned it out) puzzled next stop a new heater core? a/c evaporator? thanks

 

[CMullen]

do you have the button depressed for the air conditioning, usually represented by a snow flake. make sure it is on that should eleviate the problem.

 

[lumberjack98]

I don't see a button on my truck I think it is automatic depending where the selector is placed. wish it had a button or some way i could install one to run the compressor. thanks

 

[johnsogw]

how about to much mositure in the cab itself???????????

 

[Learguy]

Never had that issue until I moved to Nebraska. The '03 did it, my '02 does it, and my '96 does it. Never happened in KS, OK, TX, CA, or anywhere else. I figured it was just the right conditions. It gets your attention when leaving work, putt, putting along, waiting for heat to build, get a little heat on the gage, turn on the defrost, BANG! Windows fogged over! No I go to floor heat first with the window cracked, then to defrost!!

 

[2-ND TIME]

If you engine is cold when you start it is only then that there is enought heat to dry the windows off. Are the mats on the floor damp,wet or fairly dry? Any moisture on the floor will keep the windows foged up . 95% of the time I run with the heat selected on floor this keeps warm air ( I can tell when the temp goes down 1 degree outside. ) If you can keep the heat off the window if doesn't melt the snow if it lands on it and only bounces off. This doesn't work if stop and go traffic or ???.

 

[TurboFan]

I suppose you have made sure the AC is working properly (not just compressor running)? As you know that dries out the air when defrost is selected.



Just a shot in the dark... is it possible the air intake has accumulated moisture due to a plugged drain? Pine needles are insidious.



I have rarely had fogging issues. I'd say that waiting for engine temp before turning on the defrost is not as good as defrost at engine start. That way you're not throwing warm (moist?) air onto a very cold condenser. I mean windshield.



'Good luck