Could be just worn out. This vehicle is 12 years old. I would replace all the vacuum hoses, if you haven't done so before.
The 1994 Cavalier creates a vacuum from the engine. There are vacuum hoses all through the engine bay, and under the dash.
Vacuum leak. Replace all vacuum hoses under the hood. Replace one at a time as to not get confused.Vacuum leak. Replace all vacuum hoses under the hood. Replace one at a time as to not get confused.
When this happened to me it was the three vacuum hoses on the transfer case switch were on wrong. There is a nipple on the switch and a hole in the vacuum hoses.
There are several vacuum hoses in a trail blazer. Any of them leaking can cause ac vacuum problems. Look under the dash to see the in the vehicle hoses. It would be a good idea to get a vacuum diagram of the vehicle and check all of the hoses.
The Beam Central Vacuum system would occasionally require replacement of parts for continued use as these parts do wear out. Some parts and accessories would be a vacuum hoses, as well as replacement attachments for the system.
To fit both those symptoms it would be a vacuum leak, check all the vacuum hoses and the intake
Well that can be tough as vacuum leaks are sometimes troublesome for great mechanics to find. My best advise would be to use the process of elimination in order to pinpoint the direct problem. Start by acknowledging the good hoses from the bad. Then once you have all of your bad you want to replace them. Its about $1 a ft. its going to be the hoses associated with the intake so I would begin with those hoses
Several possibilities...the most likely would be vacuum leak. Check for loose or split vacuum hoses and intake manifold gaskets.
Only if your brake booster has a vacuum leak, or the hoses going to it.
where the intake manifold attaches to the head, and along any of the rubber hoses that are attached to it.
Sounds like it may be a vacuum leak Check fittings and vacuum hoses under hood, under dash and at vacuum modulator on transmission
If your Silverado is like most other cars today, it will use vacuum hoses to change the distribution between each setting. The vacuum in the hoses is created usually by the engine, and transferred to the switch you use in the cabin. Now if there is a slight split or crack in one of the hoses or one is loose this will lose the vacuum, which is why it will not change setting because there is no negative pressure to force the setting to change.