1988 XJ heating/AC vents not working

[pdlee]

Any of you ever run into this problem? The heater and AC work fine, but I am only getting circulation from the defroster vent. The others will not open.

I'm positive it's some sort of vacuum problem - any thoughts or recommendations?

TIA!

[JeEpBoY95]

my jeep has just started doing this! what does it mean?

[JeEpBoY95]

after i jiggle the controls a little i goes back to normal

[bobv872dr]

The lower dashboard vents in my 87 cherokee also just stopped working. All cooling discharge air comes out of the defrost vents. I believe this is the default position for all of the flapper doors when the control lever is in the off position. I suspect either a broken vacuum line somewhere or more likely a bad contact in the control switch. Please let me know how you resolved your situation

thanks bobv872dr

[JKooshTJ]

Man and I thought I was the only one. I have a 1988 Cherokee and it's stuck on defrost also. I assume that a vaccuum line is loose or bent or something. I'll check it out further and let you guys know. I have to get back to fiberglassing in the new floor!

[debb718]

wow me to i have a 87 jeep and doing same thing blows cold air out dash only let me know what you guys find out

[884Banger]

I had a similar problem. The A/C and Heat worked, but nothing was cominig from the heater vents. There was a vacuum line disconnected behind the dash. Once I reconnected it voila!! all was well. 1988 Jeep Cherokee 2.5L TBI

[Saudade]

Most likely a vacumm line has dislodged or broken from the control ass'y.

If you remove the front panel and the radio, you can see the connections.

[chefchas]

Had the same problem on my XJ. Vacuum lines all checked, searched everywhere for vacuum diagram. Couldn't find squat.

I found a tiny vacuum leak up by the battery where the lines go down to the vac canister. I fixed the break, air blows hard and cold. Keep looking for that leak. It's not the control levers. Good luck

[bobv872dr]

Problem solved. Same location you mentioned. Vacuum line disconnected from cannister down below battery. Reconnected worked like a charm

Thanks All the Same

[JKooshTJ]

OK I finally have air blowing out of all the vents...problem solved right? I'm not sure. I believe that I have it working but not the way it was intended. There are 2 vacuum lines coming from the firewall on the passenger side for the A/C system (white & black). The white one is connected to a vacuum canister (small) near the passenger side of the engine. The black one is a really long tube which I believe this was the one going to the vacuum canister behind the front bumper. This is where it gets interesting. I've never seen the vacuum canister because frankly I don't have one due to the XJ being in a front end collission before I bought it. So this guy just had the line sitting in the engine bay. (This would explain why everyone says to look under the battery for it and it wasn't there).

I also have one more loose vacuum line, this is the best description of where it is. If you are in front of the jeep looking at the engine bay, there's a hose coming off of a connector on the right side of the engine, on top, behind the fuel rail. This hose has a suction to it. I have no clue what that's supposed to go to. Here's the interesting part. Since I have no idea if the black hose from the firewall was the only one going to the cannister behind the bumper, out of desperation I attached the two hoses end to end and VOILA! I had air coming out of the vents. I completed the vacuum cycle, but is this the correct way to do it? Is there another line coming out of the vacuum canister going somewhere? I just want to make sure this is correct and that I'm not inhaling engine gasses and I'm gonna die down the road somewhere. Thanks!