most likely condensate from the pan drain being clogged. check the pan at the base of the AC and see if water is overflowing. the drain should be going to a sump pump, often the same as the shower sump.
but it could be a leak in the water line, which is more serious if it gets worst. where is the pump? if in the engine bay as on many small boat the water hose is routed forward to the AC unit.
oviuously a clogged strainer would mean no water is being pumped so no water would make it inside. and your AC would shut down with a high pressure error