Has anyone seen this vacuum line split?

It took me a couple of days in frigid weather, but I finally tracked down my HVAC vacuum leak.







It's fixed and all the vents work fine now, but I'm just wondering how the heck that line could sever like that? Has anyone seen this particular spot go bad?

Many threads on this forum helped me to figure out this issue. This place seems like a great resource for my new-to-me '99 sport.

Cheers!

Pictures aren't working.

MT Mike said:

Pictures aren't working.

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Fixed, I think.

As the tube gets old, it gets brittle. It gets worse when it is cold. Just vibration can cause it over time.

old_man said:

As the tube gets old, it gets brittle. It gets worse when it is cold. Just vibration can cause it over time.

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Ok, thanks...good to know.

Old_Man is quite right. My experience with XJ vac lines is similar to yours: Heat, Cold, Vibation, the very essence of XJ experience, can do this in weird places. Had this happen on my 86 XJ at the front axle disconnect line. The tubing leaked at the connector to the axle servo. Caused all kinds of low vac issues elsewhere. Dealer could not find it. I finally located the issue by capping off various vac systems on the XJ. Used Shoe Goo to fix it. After paying hundreds of dollars to the dealer for nothing. Its no fun digging out your dash for a ten cent fix. But just be glad the split was visible and not somewhere under the tape that wraps the bundle! Which suggests a good inspection of it all is in order if you have that area dismantled.

Your pics worked great and explained the issue real well.

Great picture to help further explain vac issues with the HVAC system. Some folks give up searching at the engine bay. Lesson here is even if you've checked all the "usual suspects" under the hood, that the vac lines continue inside the dash where the HVAC action really is. It applies to Renix/HO's/later models and even other vehicles (my Astro van had the same set-up). A little different configuration but all relevant to HVAC phantoms.

Yeah, guys, I spent a bunch of time capping the t fittings under the hood, cutting/capping the line to the firewall, and I kept getting good suction. This is a non-cruise control model. I finally made it to the connector behind the glove box, where there was again good suction, so that left the very last piece of the puzzle. It's actually not that hard to get into it all, as most of you already know.

Just for informational purposes, the vents all switch and function fine with the t fitting capped at the firewall as long as you don't have CC.

I really look forward to learning a bunch more about this vehicle as the weather gets warmer. I've only had mine for a week now, it's my first Jeep. I love the vast amount of data that's available for DIYers with these rigs.

Cheers!