the last few mornings ive left for work it has been a little chilly i start my car turn the defroster on set on hot fan on high.the window will defog.when i get in and drive down the road the windows will fog back up again.and the defroster will only clear a small patch right above the dash vents.ive had to drive to work this way the last 3 days.the blower motor seems to blow hard it's not making any noise and works on all settings.could it not be blowing hard enough or could it be something else?

 

If the air is hot coming from the vents, i would suspect you have a leak in your heater core. Has it ever been replaced? does the car have a oily film on the inside of the window? Is the passenger side floor wet? Check the last 2 things out then report back.

 

no wet floors,no oily film,not over heating .it blows cold if i set it on cold and blows hot when set on hot everything seems to work fine just wont defrost the whole windsheild.as 4 the heater core ive.only owned the car 4 about 2 months but i doubt it has been changed or the blower motor for that fact

 

Try setting the temperature in the middle. The goal is to have dry air across the windows, not necessarily hot. The hot air you're generating may be too hot and carrying too much moisture.

 

although that sounds reasonable why would it clear 2 patches right above the dash top windsheild vents aprox 10 inches long and aprox 8 inches high and not the rest of it? its just enough to see if i sloutch down.but boy do i look like an a$$ when i pass people i know lol

 

Because that's where the air is hitting it? I don't know, but my mom's taurus did the same thing. Full hot it would fog up again, but in the middle it worked great.

 

If your AC compressor isn't working then the defroster will work dismally. The dry air coming from the A/C is really helpful. Also like others said, the warmer the air the more moisture it carries. You're prolly just making the areas that are clear warm and the rest of the glass is cold causing even more moisture to condense on it.

 

alright fellas heres a up date get this i was on my way home last night and the heater core BLEW antifreeze all over my pass floor gess akmusclecar hit it on the head so i bypassed it for now thank all of you for your help