RegularGuy

So the WJ finially came back from the shop, but it needs a wheel bearing and a few other minor things.

The most annoying of which is a leak somewhere in a vacuum line, the HVAC/CC system. The cruise doesn't work and it only blows on the defrost.

I hate vacuum problems almost as much as electrical ones. Ive checked from the intake up to the firewall and along the back, to the 'T' where it goes into the firewall and such, that seems good. From there, of course, it makes its way under the battery. Is there a way to check to see if the leak is under the battery area, without having to tear out the battery and tray, or off the headlight? I'd really prefer not to rip everything up.

dave1123

Underneath the battery is the vacuum reservoir. Just plug the line and see if everything works. If it does, either rip everything apart or buy a JY reservoir and mount it somewhere. Some that I've seen are a 4" plastic ball. All it's used for is to close the heater control doors after the engine shuts off, but if it's leaking it won't allow the heater controls to function. It could just be a bad hose under the battery. This vacuum source is also used for the cruise control.

RegularGuy

right, the CC is out.

So. i need to take out the battery and tray to check to see if the hose is bad, then?

dave1123

No, just follow that hose to it's other end, disconnect it and see if you have vacuum there. If you do, it's obvious the leak is under the battery. It's basically the same thing as checking for a break in electrical wiring. Keep going back toward the intake and checking. I'm not trying to insult you by stating the obvious, but you need the engine running to do the checking.

I couldn't find a vacuum circuit diagram anywhere, but there should be a check valve somewhere in the system.

Just a thought. On the WJ, the heater is controlled by stepper motors (electrical) and not vacuum. The CC is also engaged electrically so your problem may not be vacuum.

What work was done at the shop?

RegularGuy

Well thats a sore subject. Originally it needed engine work (two piston skirts, ouch).
Then the guy wennt ahead and replaced a bunch more shiBe not on the estimate without asking or notifying about them until the vehicle was done and needed to be picked up, and the balance paid. total time in his shop was 4 months, much longer than the 2 weeks on the estimate.

So the engine worked on, i think front axle work, all new brakes, a battery... i think that sums it up.

Anyway, i didnt think i could get y hand down under the battery to find where it ends so i didnt think i could disconnect it. i did check over the other way, where it terminates on the intake, and thats connected right.
It seems that her exact symptoms are reported by many on different forums, and its always a vacuum leak. so i figured it was the same.

dave1123

No, I meant to take it apart at the "T" near the firewall. Plug the one side of the "T" and then see if your heater and CC work.

If he replaced 2 pistons, chances are he removed the engine to do it. If so, there are so many things he may not have reconnected. Good luck with that!