With the window down all the way, you can spray penetrant into the gap where the window goes trying to hit lock cylinder and use generously and try to work the lock. If that doesn't work then you'll have to remove the inner door lining to gain access, but it can be a pain when the door is closed.
Google 1996 Buick Regal Custom and see.
where is the drain plug for the radiator on a 1992 buick regal custom
Freon valve on my 1989 Buick Regal Custom 3.1 V-6 located on driver side under the area of battery tray. Hope this helps!
the rear door of the 94 buick regal is locked & will not open
the PCV valve is located on the valve cover of a 1991 Regal Custom. It is plugged in and can be easily changed.
The Engine Control Module (ECM) on a 1988 Buick Regal Custom is typically located under the dashboard on the driver's side, mounted to the firewall. You may need to remove a cover or panel to access it. It's usually positioned near the brake pedal and can be identified by its rectangular shape and wiring connectors.
Ebay has several most of the time, search 91 Regal
A 1994 Buick Regal Custom uses 134a refrigerant, not freon.
the doors are being placed in locked position If it's coming from the engine or transmission area, I would suspect a cracked flywheel or flexplate.
no
The PCV valve on a 1994 Regal Custom should be located on top of the valve cover. It is a plug in type and is easily changed.
Glove box