Orca, I (and another guy) had this exact problem in 2014! Here's the thread: https://www.dutchmenowners.org/forum...rain-1883.html
Camping World said I had no problem, yet when I pulled the AC myself, I could see where the water was running down the inside of the wall. The culprit was all in the mounting of the AC and the drip pan below. It wasn't a hard fix, except for scraping out all that caulking. I mounted the pan more securely and used washers for a tilt. Good luck!