Mid vents don't blow

There is a vacuum hose that is no longer connected to the engine intake manifold.

Could be a vacuum actuator problem. or just a vacuum leak, period. I have a Jeep that when it has a vac leak, the climate system defaults to the defrost, no matter what you set it at.

It's most likely a vacuum line, look under your hood (close to the cowl panel) for a disconnected, cracked or broken vacuum line.

In some rear cases, it could be the vacuum switch (in dash). Or vacuum diaphragm (under dash).

Hope this helps you ???

The actuator door for the middle ducts is not opening.

There is a actuator motor motor that is not working in the dash,that will have to be replaced,the dash will have to removed to repair the problem.

There are no grease fittings on your Buick. Most manufactures started using sealed joints in the early to mid 90s. If a joint is making noise it will have to be replaced.

the vents are run on vacuum so if you get the others just not vent sounds to me like you need to find your junction and see if all the hoses are hooked up. mine was passenger side above where ur feet go. All that usually happens is a hose came off and u need to put it back on sometimes they break but u will be able to see once u find it.

Fuse box on a 2000 Buick LeSabre is under the rear seat along with the battery. Simply pull up on the rear seat to remove,

check your vent adjuster switch

if car has had dash work vent tubes may not be attached to vent opening if the job wasnt done properly-or tubes may be cracked or missing