Yes the vacuum bottle is located at the bottom back portion on the center console.

It is accessible from the right side by removing the plastic panel. A upper screw and one twist clip at the bottom. The rear of the panel engages a push clip mounted of the footwell wall.

You will find the white bottle with a hose coming from the engine compartment, that has that check valve mentioned in the other post, to the one end there.

From the bottle the vacuum is distributed by the push button control panel.

In some cases it can develop a leak within it but it's just as likely the a vacuum motor or operator of the duct flaps has sprung a leak in its diaphragm.

I surely hope it's not the one behind the heater core that closes the outside air duct flap.
I have one on my '91, it is impossible to reach with out pulling the console.

It is presently operated by a nylon rip cord, like off a lawnmower routed to the open box under the push button control. I hook it to a bracket until I use the A/C and close it!

If you have access to a hand vacuum pump, it makes the job easier to trace, otherwise the job might suck! 🙊

Gook luck,
Phil