Cold water leak inside on Driver's side.

What is your question?

I assume I have a plugged drain line, but I am not able to locate the drain. Can anyone tell me where it is located. Please note I am talking about a 1986 Lincoln Continental not a 1990. I had to select 1990 because that is a far back as the selection table would allow. Thanks for any help received. Owner of a 25 year old Lincoln.