JPHunter91

I'm at a loss as to where to even start to look where my problem might be. I've tried searching this forum and a few others and still can't seem to find an answer so I'll ask you fine people. Anytime I'm on the highway using my cruise control the blower for the a/c either switches to just the defrost or shuts off completely. If I'm going up hill or doing anything faster than 75 and try to have both systems on the cruise will sometimes just completely shut off. I know this is one of those first world problems but I do a lot of highway driving and it would be nice for the cruise to work.

CCKen

You have a vacuum leak.

Open this link and scroll down to post #51. It shows all the vacuum tubing in the engine bay. Inspect all of the tubing, including the vacuum reservoir under the right front bumper end cap.

https://www.cherokeeforum.com/f2/gre...e-6558/index4/

JPHunter91

A couple months ago I moved the vacuum ball from the bumper to the passenger side of the engine compartment when I swapped bumpers and broke one of the lines going to it so I replaced all of the ones I could find that were brittle. Anyways I guess my question would be is there a way I can check them other than just visually? They all seem to be fine to me

CCKen

There should be a pic of vacuum checking the system using a vacuum brake bleeder hand pump (Harbor Freight). Worked good for me. Just hook it up at the intake manifold rubber coupling and pump the system down to around 20"/hg. It should hold.

If the vacuum does hold, remove the check valve at the intake and blow through it. It should be free one way and block the other. If it free flows both ways squirt some Liquid Wrench silicone in both sides of the check valve and try it again. If it still flows freely both ways, replace the valve.
Make sure you mark on the valve which way it goes before removing it.

JPHunter91

Thanks for the help, I'll update when I get a chance to try that.

JPHunter91

Turns out the elbow that connected the line to the vacuum ball had a crack in it, replaced and everything works great now.

CCKen

Good work, and thanks for the follow up.