Researching why CC not working on my 93 XJ.

No CC light on dash
Horn works
Cruise control does not do anything
Heat and air are on defrost only....does not switch to vent and/or floor

It looks like its a vacuum line issue which seems odd but....
When I looked online I saw a canister of some sort near the front bumper. I dont have a front bumper on my new to me XJ :-). There is definitely a vacuum line up there that was zip tied off. Do I need to just plug all the vacuum lines or am I screwed because components of the system are likely missing?

Rob

 

You lost vacuum. You need to trace the vacuum lines and terminations to find the leak. The feed is off the intake manifold and then goes to your HVAC control in the cabin and across to your cruise control servo, which is typically on the right inside fender and vacuum reservoir in the right front bumper. On my 96 the vacuum line for the HVAC control enters the cabin through the firewall via a small capillary tube on the right upper side.

 

Oh, what you're saying is you are new to the Jeep and notice stuff not working because it's had the magic screwdriver applied to it. Yep, you need to see what's missing.

 

So it looks like the vacuum reservoir is no longer there. Id I dream the system and restore vacuum will that fix the issue or is the reservoir necessary for everything to work?

 

You need a reservoir. Doesn't need to be behind the bumper (that you don't have) but needs to be in the "circuit". Many folks relocate the reservoir in the engine bay when they install custom bumpers.

You need it because engine vacuum can vary greatly depending on engine load. The reservoir stores "vacuum" to keep the HVAC doors, and Cruise control functioning during periods of low vacuum (e.g. accelerating, hill climbing, towing). There are also several check valves to maintain the vacuum.

 

Crap....this sounds like it's going to be a pain in the ***....

 

No. It's just something you haven't become familiar with yet. Start identifying the cruise control engine bay parts that are or are not there. Look at your throttle body linkage. At first glance you should have three cables going to it. One is from the accelerator pedal, another is from the cruise control servo and the last one is from the transmission (TV cable). I think the one in the middle is the cruise control. If that's there then your servo is on the other end. It should have a vacuum line going to it that's "tee'd" off with one line going to the vacuum source (intake manifold) and the other to the vacuum reservoir. If the PO removed the CC system he probably would have cut off and plugged the vacuum line before the "tee". The parts are probably readily available on the after-market cheap. Regarding your HVAC system, that requires a vacuum line entering the firewall as I mentioned above. being a 93, it stands to reason that the original line has become deteriorated and cracked, or possibly broken. That should be found somewhere on the firewall upper area towards the right side. It's that or the line is broken at the HVAC control, which requires removal for inspection.

 

It looks like this image is going to be my friend

 

Perfect. You can see where the line entry point through the firewall for the cabin controls (Heater-A/C) is. My line broke right there and I ended up getting a piece of suitably sized rubber tubing to bridge the gap. Still working. At the moment you probably want to get that going before any further work to restore the CC system. The heater-A/C does not need a vacuum reservoir. You'll need that to keep the CC servo vacuum pressure stable.

 

Is there a cruise control indicator light on the dash? Is it expected that would not light up without that vaccum in place?

 

Yes, but I think that light is enabled by a switch in the servo itself once it's engaged, meaning it has to be present. Or, if the vacuum supply is appended before reaching the servo your indicator would not illuminate. I can try removing the vacuum line from my servo tomorrow to confirm this.

 

Thank you a ton for the info. I ordered a canister off Amazon a few minutes ago. I will get to tracing lines this weekend. I'll update the thread as to what I find as I hate threads that die without a resolution :-)

Had a big dirty project this last week doing tie rod ends/control arms/ball joints/wheel bearings/track bar etc. to fix a wobble. Wobble is completely gone now it will be nice to work on the cleaner more optional fixes.

 

Old jeeps are gonna break so expect this place to be your assistant to fixes. On my 96 and 98 the first thing I did was clean the doghouses top to bottom and backwards underneath where oil was spread. Then I found and fixed the leaks. I don't mind getting dirty (45 years as an aircraft mechanic) but I keep the vehicles clean. It makes servicing and maintenance less odious and much easier to spot problems. And, they're just a little bit cleaner after each service or maintenance because of the "while I was there..." thinking.

 

I stand corrected on the CC-enabled light on the dash. With or without vacuum it illuminates when the CC is On. I have to push the CC ON/OFF and Coast buttons simultaneously to turn the CC On as well as to turn it Off.

 

SWEET!
Installed the canister today. Bought from Amazon for $15. Hooked up the one vacuum line which was still in tact dangling near the front passenger side headlight. There is not room for the canister behind the battery where it seems many people mount theirs. I think the location of the battery may be different on a '93. I simply set the canister near the oil filter. I will find a more permanent location later.
Cruise works and HVAC switching between the floor/vent/defrost works perfectly. Two fixes in one!...and simple to boot.
The only thing that might be an issue is there isn't a light on the dash when the cruise control is set. Do 93s for sure have a light?

Thank you for your help so far...super happy.
Rob