“Ok – problem solved. I had some work done on the boat over the winter which included the installation of a new shower sump box, float, and pump. The whole box was replaced as well. Anyway, when the new box was installed, the hoses were swapped. Meaning, the A/C drain hose was connected to the discharge side of the shower sump pump, and the overboard discharge hose was connected to a regular drain barb on the new box. So, the condensation from the A/C was flowing normally down the drain hose, but had no where to go once it hit that one way pump. It ended up filling up the drain hose and eventually backing up enough to fill the condensation pan. The whole time I was snaking the overboard discharge hose. Anyway, once I disconnected the A/C drain hose from the wrong barb on the sump box, water flowed out until the drain pan was empty…..”