where is the ac drain on a 1996 caprice and can it leak inside

It should be a plastic nipple on the passenger's side below the heater plenum (box) You may have to get under the car to find it. Yes, they frequently plug up with leaves and debris.

okay, I know what this is now, at first I thought that you meant coolant...to drain it unscrew the shroeder valve, gas will leak out~ are you gettiing condensation on the inside of the cabin...well tell your mechanic to blast the drain clean there a little tube coming out of your heat exchanger just for this purpose...use a pin air blaster on it...that's why we suggested as seeing a mechanic because they will not sell these to people for safety reasons~ooooof~