Join Date: Jun 2004
Location: Portland, Oregon
I had the same thing, and took about a week to find the root of the problem.
Question that may help further diagnose the problem though...
Does your heater box make a "clunking" sound when you accelerate or brake? If it does, than most likely you have a broken control arm on one or more of the heater duct rods.
If it doesn't, check the vacum actuators. So here's what I would do.
First - Let's look at the vacum actuators.
1 - Get your head underneath the paneling on the drivers side - this is not fun, but you'll see where I'm going once you get there.
2 - there are 3 silver "cans" with 2 hoses on each one, and a lever coming out of one end - these are your actuators
3 - Start the engine, set the brake and find a friend - you can do this by yourself but it's a PITA.
4 - Turn the fan on LOW
5 - Move the selector lever from one setting to the next SLOWLY! Give it time to settle. As you move the control, the "cans" should move in and out, but they don't all move at the same time for each setting (top one is for the defroster, I think the bottom is for the floor vents, and you can guess what the middle does.)
6 - Check all the selector positions - if none of them move, then you have a vacum leak. If this is the case, better go find a vacum gun and figure out which one is broken.
If by chance you don't have a vacum leak, it COULD be the actuator cans themselves - they have a rubber diapraghm that potentially could break and cause it to not work.
Alright, if you've determined that the actuators work, time for the tough one.
This is to check the actual control arms.
1 - take off the plastic panel under the steering wheel
2 - take off the metal plate behind that
3 - find a flashlight (worklight on the floor of the jeep works too)
4 - Turn on the engine
5 - Move the control slider to the different settings, and watch the moevement of the arms coming off the silver cans.
6 - if the arms move, but the black plastic levers don't, they are broken.
7 - to remove a broken plastic thingy, there's two methods
7A - take the silver vacum actuator off, and grab the plastic arm with a pair pf pliers and pull really really hard straight out. It'll pop off eventually
7B - if it's like mine was, then the arm broke off inside where you cant grab it it get's even tricker. Get a really long decking screw or similar and drive it straght in. Grab the screw with the pliers and pull
8 - finding a replacement is tough - there's a jeep recycler on line (can't remember who it was, I'll go look when I get home) that MAY have these. If you go to the dealer, they'll look at you like you have 4 heads and try and get you to buy a whole new "Blender Box" which is what the heating system is refered to. DON"T DO IT. You only need the plastic arm, but even that will set you back $25 from a recylcer.
For some reason, these plastic things break all the time, and Jeep doesn't offer an "Off the shelf" replacement part. Stupid stupid stupid. If I had an injection molder, I'd start making them and selling them!
Hope this helps.
'97 Forest green. ~6" total lift, 8.8, etc. 36" TSL's, winch. You get the drill.