Where is the air conditioning drain plug for a 2001 Buick Regal?

There isn't a drain plug in the typical sense for the air conditioning system on a 2001 Buick Regal (or most cars). The condensate drain is a small tube or hose that drains water from the evaporator case. It's usually located inside the passenger compartment, somewhere near the firewall, often behind the glove box or under the dashboard.

Finding it requires some searching and potentially removing panels. You'll likely need to consult a repair manual specific to your 2001 Buick Regal to pinpoint its exact location. A service manual will show diagrams and explain the procedure.

Warning: Attempting to access the drain without knowing the location can cause damage to your vehicle's interior. If you're uncomfortable with this task, it's best to take your car to a qualified mechanic.