I can get all speeds of the blower fan but now it only comes out my defroster. Been making for some uncomfortable early morning drives to work, at least for 15-20 miles.

Any ideas of what I should look for? It's not the lever slide style, it's the **** style heater panel if that helps.

 

Look for vacuum leaks.. if it doesn't have vacuum, defrost is the 'default position' for your vents. Behind the rotary type vent switch are several vacuum lines to check too.

 

Are these lines easy to get to? Or are they tucked behind a bunch of stuff? Can they be looked at from inside the Jeep?

 

Where are the blower motor resisters? I was told to check those also.

 

The blower motor resistor is what gives you different fan speeds.. if it's burnt up, the fan motor defaults to high speed; that is, it would blow on highest position, but not on 1,2 etc. That shouldn't be your problem.
I'd check behind the controls (yes, inside the jeep) I'm not familiar with xjs but you can search for a 'how to' article here on the forum, or google it.

 

If you get all speeds from the blower fan, the resistor is OK, no need to do anything with it.
Vacuum hoses are in behind, yes a bit of a nuisance to get to. I think the problem is more likely under the hood. Do you have cruise control, does it work? (it runs from vacuum also).
Not sure about '99, but in earlier models there's a vacuum storage bottle just inside the front bumper (right hand side). It's black, rounded ends, about the size of a thermos bottle. Check the vacuum line to it too.
I suspect you'll find a rubber fitting rotted off, or a plastic hose pulled out of a fitting somewhere.

 

No Cruise control. It's just a base model XJ. No power seats, windows.

 

There is a bottle on the front bumper and the hose was disconnected. Now all of my blower vents work.

Now, that raises another question if you don't mind.
My blower seems to switch vent locations whenever it wants. One minute it'll be coming from the dash, then it'll switch to the defroster, then to the floor, then dash again. There isn't a pattern, it just does it.

 

It still sounds like a vacuum issue to me. Now you have the vacuum available to the controls behind the ****, but if they are cracked, leaking or unhooked, it will keep defaulting to defrost. It might look difficult to remove the control panel, but look closely and you should find a couple of screws to remove.
Again, my only experience is on Grand Cherokee Laredo models (a '93 and an '02) but that was where I found the problem on those. Hope this helps

 

^^ X2. You still have a vacuum leak.
I bet it switches to defrost when you step harder on the gas, like when you are going up a hill.
Why was the hose to the vacuum bottle "disconnected"? Did it fall off because the rubber fitting is old and crappy and split? If so, there are probably other connections in the same state.

 

It was in perfect shape. Don't know why it was off.

I plan on checking behind the panel today when it warms up.

 

'99 XJ here, circled/arrow pointing to the vacuum line connections. You do not need to remove everything I did, just the glovebox assembly I believe. It's gonna be hard to tell without a vacuum tester (like 60 bucks-ish) however unless they are visibly cracked/cut/damaged they are most likely fine. Other issues can be the actual switch, because it's connected directly to the vacuum lines.

 

Haha, dan91, glad you have a pic. As for op, I'd agree and say that there is a vac leak still. The issue may be up close to firewall where the grommets for vac lines are. This seems a common spot for corrosion and wear. But pull the glove box out (3 screws on the bottom of it) and you will have a pretty good view of the lines. They are all colors of the rainbow, btw..

 

check valve in vacuum ball is possibly shot, install a in line check valve in ther supply line to the ball seee if that cures it

 

Vacuum ball? Can I please get pointed in the right direction on this part?