ok my dad recently got a 97 cherokee, the defroster dont work, you can hear it blowing, it comes out of the side window defrosters, just not the middle windsheild defroster. also the main vents dont always work, but sometimes do. you can always hear it blowing, it just dont go where it needs to. the foot heater always works. but again, the mIddle defroster doesnt work, and the heater vents sometimes dont work.

Also, it blows warm, but not hot air. not as warm as my 93 cherokee. something else i noticed, it seems to register at 180 degrees on the temp guage, not 205 like my jeep and every other jeep i see.....is this something that changed in 97 or did someone switch out the 205 thermostat for a 180 thermostat? and could this be causing it to not blow as warm? thanks for any info

 

Try flushing out the heat core. See if you have any junk blocking it up

 

It should have a 195 thermastat in it, and it sounds like your blend door isn't working like it should.

 

I'd start here.

 

back flush the heater core. i have a 97 and when bought mine it had very little heat then i back flushed it and all kinds of crap come out of it. now it cooks me. the blend door is not operateing correctly

 

This for the temp…
This for the airflow...

 

where is the blend door? can i get to it from inside by removing part of the dash or is it located somwhere in the engine compartment

 

If I remember right it sits behind the glove box, the glove box will swing all the way down once you get it past the rubber stops.

 

I had a similar problem last week. it turned out to be a cracked vacuum hose behind the battery going to the vacuum ball. i just cut out the cracked part and joined the two ends togeather with a pice of rubber tubing. remember all the doors that direct the heat to it's proper place works off of the vacuum system. a borken hose or tubing or simply a hose poped off somthing will cause all the problems you are having. when the jeep is running listen around under the hood for any hissing noise. you may have more than 1 crack or hose fell off somthing so check this before you go crazy.
hope this helps.

 

I'm also having the same problem with my heat and air. It's not going where it needs to go. Only thing that works is my defrost.

 

put your temp dial on full heat and put the other one on vent, if you get heat then you know you have a problem with the blend door. Thats how mine is but i dont feel like tearing into the dash to fix it.

 

Sounds to me you have a vacuum leak. all the accuaters that open and close the doors to direct your heat work off vacuum. inspect all your hoses under the hood. find the vacuum ball if that is cracked that will do it too.

 

If you look at this diagram when the valves are in NO VACUUM postion "NV" it will close your floor and dash vents and blow out your defroster

 

1999 Jeep Cherokee -I back flush the heater core and now have plenty of heat!,Then bough a Peak back flush kit, and did the whole system with a Peak system cleaner.(There is no control valve) Both hoses from the heater must be Hot. The intake is the top one come from the engine block, bottom one come from the water pump.

 

Unfortunately, it is possible to buy "cooler" thermostats. A lot of people are misguided thinking the cooler the better.

The 4.0L does not want to run cool

The hotter it can run without overheating the better. 195F or 90C is the factory recommended temperature.

It will actually be better on gas at those temperatures then cooler.