My AC ran good one weekend. I trailer the boat. The following weekend it didn't.The pump doesn't seem to move any water and suddenly growl and stopped. It was a taylor model (5) years old. I replaced it with a March LC-2CP MD equivalent. The new pump doesn't seem to move any water.I Opened the discharge, and added water through the strainer and it comes out the pump, but with no pumping action. Nothing else has changed in the AC system. Does the boat have to be in water to check it out? Can't it be done on the trailer? My strainer is clear and all of my lines to. I blew them out with air. Can I only test it in the water. The pump is in its original position. Being a centrifugal pump does it need in a closed environment pressure of the surrounding water pressure. I was hoping not to have to take it to the Lake Huron to to find out I still have a problem?