Finally got the XJ on the road today, and the A/C even works.

But, under a load, I get what sounds like a vacuum leak in the dash, and the dash vents stop blowing....until I let up on the skinny pedal. The sound stops, and the vents blow again, but I don't really get a solid "air door thump".

This is a 1999 XJ, but the Haynes manual indicates the air controls are behind the glove box...what am I missing before I start taking the dash apart?

 

might be a little info here to clear things uphttp://www.jeep4x4center.com/jeep-se....swf#toolbar=0

 

mine was doing this it was the check vale in the bumper mounted vacuum ball had gone bad i just bought a new valve and installed it in line not sure if theres a vacuum storage ball on your year in the same location,i did not have a hissing sound either

 

Thinking on it further (and back to my motor building days), it does seems like a vacuum loss issue, especially when things straightened out AFTER I got off the throttle...that manual link will be helpful.

I will dig into this in the morning, and see what I can find out, after finally getting it road-worthy, I want to get the little issues fixed fast, got too many big mods I want to complete before the end of the year.

 

good luck

 

Okay, well, I did determine that I have NO vacuum reservoir behind the bumper, and most of the lines run direct.

The vacuum controls for heat and air work, but they are slow...so I am thinking the missing reservoir may be part of the issue, along with maybe old lines.

'99 Cherokee Classics DID have the reservoir behind the front bumper, right?

Can I make a canister, or use one from another vehicle?