Hey hey,

I had a quick question before I pull my entire dash out.

I've got a 1995 jeep cherokee XJ with A/C. It's got the good old issue where it's stuck on defrost with a massive vacuum leak. Problem is, the hose that normally breaks by the firewall looks great. Tugging on it also doesn't make it budge. I scoured my FSM and forums to figure out where the vacuum line from the firewall is routed and managed to figure out that it goes from the firewall check valve to a split, then to the vacuum solenoid on the heater controls. It should have constant vacuum at the two black lines if I'm not mistaken.

I get plenty of vacuum at the line going into the firewall, and zero vacuum at the heater controls. My hunch is that the split shown in the diagram is where my vacuum leak is. Where the heck is that and how do I find that. Is it dash pull time?

I appreciate your time!
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While I appreciate the image, I don't believe my issue is in the engine bay. I'm looking for the split mentioned here in the FSM.


This is where I believe my vacuum leak might be, since I receive no vacuum at ports 11 and 2, but full vacuum at the check valve. The hose entering the firewall is also intact.

Thank you.

 

So you pulled out the heater control, disconnected the vac harness and tested for vacuum? I'm not exactly sure where the split is located. Sadly, it may be tucked in behind, or on on top of the heater box.

Here's one from my '88 (a spare I got from a JY, Someone else took it out but left it behind). You can see the lines on 10 &11 on the right, and the black going to #2 just to the left. There's no "split" within a few inches of the control so it must be further back.

 

Yeah I pulled the heater controls and checked those tubes for vacuum.

It looks like I'm pulling the dash. Gross.

Don't suppose anyone has had any luck fishing a line through with a coat hanger? Maybe I'll give that a shot first.

Thank you!

 

I fished a new piece of vacuum piping through the firewall on my wife's Grand cherokee with success.

 

There's no fishing a line through or replacing that line without removing the heater core. It's taped in with a clip behind it, running next to the coolant lines.

Lucky me, I figured out that the line is just fine after I removed the entire dashboard. It turns out that the vacuum elbow in the engine bay had collapsed. If you rotate it 90 degrees it works just fine. Holy crap was this a lot of effort for a simple fix.

I replaced the vacuum elbow with some 1/4in line and bingo, vacuum in the cabin.


Here's the vacuum split I was thinking was the issue. It's accessible without pulling the dash. It's just behind the manifold about a foot.

And here's the magical fix that would have saved me two hours.


And just for good information, vacuum lines are wedged through here:


You can barely see one clip hiding underneath that rail.

Going to go and contemplate life with alcohol after knowing the fix was rotating an elbow fitting.

Thank you for your help.

 

I have played with the vacuum lines and believe you could push one through the firewall closer to the passenger side of the vehicle. There is a wiring bundle that goes through the firewall there. Just pull back the rubber grommet and push your line there and connect to the climate control like the original one did.
After doing a heater core replacement and having to pull the dash, I don't think I would do it again for a vacuum hose!

Glad you found your problem and sorry you had to put so much into it to fix it. The good thing is according to your post time stamps, you are pretty dang fast!!