Front Windshield fogging problem

[gm94]

Hi all. I'm having this problem, whenever I start the car late at night I get alot of window fogging in my front windshield. This happens if I have my a/c off. It is annoying lol. Everytime I get out of class and I step on the gas almost all the windshield fogs up. I can feel that the hot air is coming from the front heater dash vent.

What I end up doing is putting the a/c on cold and switching it to heater vent for a few mins until the fogging is gone. This just started happening a few weeks ago. I'm thinking that maybe I have problem with the gate that opens and closes the heater vent or maybe a vacum leak. I kinda looked underneath the dash for a broken hose or an airleak but haven't seen or one yet. Any suggestions or ideas? Thank you.

[Genopsyde]

that's usually a sign of a bad heater core.

[gm94]

Bad like leaking? Because I'm not smelling any antifreeze.

[nobuddie]

it takes very little heater core leakage to do this. Check clamps under hood first. It may be letting a drop run in. Then it's go to the core next. Or maybe your carpet has moisture under it. It will come out after sitting with the windows up. Maybe a spilled coke? Check all this first. nobuddie

[gmack221]

sounds like a heater core to me, or a plugged drain tube. normally there is a rubber down tube on the firewall to let moisture out of the heater core area, so it could be leaking but just draining unto the ground not the floorboards.

[nobuddie]

you know, my geo has always fogged the windows. I have thought it is because the car is so small inside. I can turn on the AC for a minute and ity's fixxed. c