I have had trouble with my 1998 jeep cherokee heating and air conditioning since I got it. I'm not so worried about the a/c but now that winter has come around, i'd like some heat.
My heat comes out of the defrost only. The vents don't work. Sometimes, a little bit of air will come out of the vents but, i can't control where the heat comes out of, it just comes out of defrost. I have checked the vacuum line from where it connects to the engine block (not sure what it is called??? next to the engine..) all the way to the vacuum canister and i have taken my vacuum canister out of the front bumper and didn't see any damage to it, but it did have some sort of liquid swooshing around in it and I was able to shake most of it out of the whole where the line connects, but some liquid is still in there. When I took the line off of the ball and turned the heat on, the end of the line where it connects to the vacuum ball was sucking air so i'm assuming there is nothing wrong with the vacuum lines. ..... ANY IDEAS? DO YOU GUYS THINK MY VENTS BEHIND THE DASH AREN'T LINED UP OR SOMETHING?

 

This is kind of a common problem with all Jeeps. It has something to do with your "blend" door. Usually the door is electronicly actuated and the motor goes bad. On some vehicles it not hard to fix while others require removing most of the dash. Try searching for a heater blend door repair and see what you come up with.

 

I've taken the dash off twice and my blender door works. What about the other doors with the little motors that have the color coded wires plugged into them? The door actuator motors might be out?

 

After doing some more research for you the other three doors are actually vacume controled. Make sure you have vacume at your control switch for the heater and then make sure you don't have any leaks at each of those vacume actuators. Also make sure you can move them with your hand so you can be sure there's nothing obsturcting them. When I bought one of my Jeeps a long time ago there was a hugh mouse nest in there because it sat out in a barn for several years...

 

Check your vacuum line running from your vacuum reservoir behind the front bumper up to where it feeds into the firewall, the line runs along the passenger side inner fender of the engine compartment. This is a common area for breaks, cracks and/or damage to the line.

 

I can hear all of the air coming into the hvac box but it only comes out of defrost and through an opening in the passenger leg area. So it is coming into the box I just can't get it through the vents. I can't find a vacuum leak. Help me please!

 

Try just connecting the lines to and from the vacuum reservoir in the bumper to each other, bypassing the reservoir entirely. Then rev your engine and see if you can change it. If you can, then the reservoir is cracked or leaking. That's how mine is working right now.

 

Btw- the passenger side air you're talking about may just be the air intake for the blower. You may or may not have double-checked this, but I can't think of why it would "blow" down there and not come out the actual leg vents on both sides. It may just be air being sucked in.

 

I may have it backwards on the revving the engine part... i don't remember. lol checked while revving and while not.

 

Hello. As mentioned the heat in XJs is vaccuum controled and if the vaccuum is lost at some point it automatically reverts to default mode which is just coming out of the defrost. Try and trace any and ALL plastic lines. As a quick example of how far away from the dash you need to look...I changed my battery a few years ago and accidentally nicked the small black plastic vaccuum line that runs along the fender right behind it. That`s all it took for my heat/ac to come out my defrost only and it drove me nuts trying to fix the problem before I gave up on all the easy/common fixes and began tracing lines.