I learned so much from this site that I figuire it's about time I give something back. Last weekend I was driving one of my 01 Devilles in a very hard rain. After awhile I noticed the passenger side carpet was very wet, running down from under the dash. My first thought was the evaporator drain, and searching through the forum confirmed that. But, I really couldnt find a good description of where it was, in the forum or the manual, other than on the passenger side down low. First I found the cowl drain, in the passenger wheelwell. It's like a flapper. It was free. Without access to a lift, I jacked up the car and got under and just started poking around looking for the evap drain. I really could not see it from the bottom. Finally I removed the passenger side wheel, and I reached in the opening above the frame, and my hand landed right on it. Just like others had mentioned, it was stuck closed. Once I opened it, alot of water came running out. No other problems since.