I recently bought a 98 cherokee sport in pretty good condition. Problem is the heater fogs up the windows and it's the dead of winter with no humidity outside. The defroster works just fine to clear up the fog, but I can't use the heater without defrost. I don't smell any antifreeze, or mold and I don't want mold to start growing in it so I want to solve it fast. What could be wrong with it?

 

hey man...i used to have this prob in my old bmw because it no longer had the AC to dry the air out, what i did was clean the windows extremely well with windex or glass cleaner then use a shammy cloth to dry the windows and remove the streaks, whats happening is there is dust/dirt on the inside of your window and the moisture is sticking to that

 

I am in the same boat with my 98- my understanding is the ac pump kicks in and out and takes some of the moisture out of the defrost air.. you should hear your electric fan kick on and off as the ac pump works.. I have to run my defrosts on every few minutes myself until the interior warms up.. already did 2 radiator flushes at the shop.. still need a heater core flush though.. hoping that might help my heat/defrost situation.. just not going to do it at 0 degrees above 0 outside..

 

Yeah, but for me even when the engine's nice and warmed up it just fogs up. Basically it makes the heat without the defrost or A/C on pointless. There's some moisture somewhere. I can feel the humidity when it comes out the vents, but it doesn't smell like mold fortunately. Yesterday and today it's been real cold and there's no fogging problem at all. I'm guessing wherever the moisture is, it's frozen now so it's not in the air. Probably needs a heater core flush like you said. I'm still figuring out the mechanics of this thing. It's my first jeep.

 

Probably a leaky heater core. Notice a sticky/sweet odor or a film on the windsheild?

 

I'm with Frank.. sounds like the early signs of a heater core problem...

 

Ok read thru all the great info - still have the issue - dry floor, cleaned windshield interior, radiator/reservoir coolant levels good, relative humidity on/off days, no ac/defrost on - still an issue at dash defroster center vents

Heater core housing [?] below glove box warm after short drive - haven't flushed yet - plugged core or core gone?

Any other possibilities? Thx

 

Heater core is still a possibility. All it takes is a pinhole. You probably wont smell it right away if its that small. Give it time.

 

Thank you - appreciate the help - also noted under the hood the ac is kicking on/off as it should based on all the information on the site Also a slight smell now


Does that help solidify your observation/input - should I bother trying to flush or just go toward heater core replacement? Thanks again

 

Zombie threads are not appreciated.