I have just purchased a 1998 Jeep Cherokee Limited, great condition but the windows fog up constantly. The defroster works blows cold air and hot air , air condition works as well. Just can not keep the windows from fogging. You can switch from air to floor , to air to face to A/C, to defrost and feel the air in the appropriate places. On defrost I get cold air or hot air from the right place.....what should I be checking??

 

is the fan operating at the different speeds or is it just one speed? It could be the resistor block. i would also look to see if anything is clogging the air ducts as well. Check to see if there is a lot of debris built up on the cowel vent in front of the wind shield. It might be worth taking that off and seeing if there is any debris or anything else in there.

 

It could be a leaking heater core. I would check your passenger side floor carefully for damp spots and trace accordingly.

 

Thanks for the replies! I got looking and it is in fact the Heater Core leaking coolant. Started to replace myself until I saw that it involved removing the dash...I'm handy enough just did not have the time. So Jeep is in the shop hopefully being done tomorrow. The shop is also going to replace the Evaporator while they are in there..
THANKS AGAIN FOR THE REPLIES!!

 

You're welcome. Good call on having the evaporator replaced while you're at it.

Thank you for coming back and letting us know the resolution.

 

If you don't mind my asking what's the total setting you back? I'm in the same boat and need to have both replaced. Just wondering what kinda cost I'm looking at

 

Make sure the shop uses a hi quality heater core. I paid big bucks four yrs. ago for a repair job that recently started to leak again.

 

Good call on your part Robert another way to tell is if there a slight haze of coolant on the inside of the windshield that can be noticeable wet or dried (not always the case but many times).