Cruise Control and Vacuum Ball Question

[Keyav8r]

Background: 91 Eliminator - cruise control would lock on and keep accelerating. I had to turn the engine off, coast to the side of the interstate and disconnect the cable at the throttle body. Picked up a "new" actuator (the vacuum motor with the cable to the throttle body) at P&P and finally got around to starting the replacement today. As I was removing the actuator I noticed a lot of slack in the vacuum line going diwn behind the bumper to the vacuum ball. I managed to move things around enough to see that there is no vacuum ball, just a screw in the rnd of the line.

My question - Could the absence of the vacuum ball (reservoir) cause the cruise to lock on and keep accelerating? Or, is it's absence just coincidental (which is what I'm thinking)? I plan to replace the vacuum ball in either case, but need to know if it causes/contributes to the problem.

[HOrnbrod]

The cruise control should shut itself off if there is insufficient vacuum, so I think it's coincidence - probably a bad actuator. Do your HVAC controls default to the windshield when going up a hill w/o the vacuum reservoir? And, since the reservoir is MIA, the inline vacuum check valve on the accessory line going to the cruise actuator might be missing too allowing vacuum pressure back into the intake manifold.

[xjrev10]

I've removed the vacuum ball and plugged the line on 2 different 97+ XJs in recent times with zero negative effects.