I have a central heat/air unit and it seems to be working overtime. Its been really hot and humid for the last couple of weeks. The unit runs all the time from noon until after the sun goes down, then kicks on and cools everything down and kicks off like normal. The drain pipe from the evaporator coil stopped up at the evaporator and water dripped out of the bottom of the evaporator and soaked the floor. I changed the filter and the old one was dirty but didn't seem like it was excessive. I got the drain unstopped and there hasn't been another soaking (it still runs all afternoon without kicking off). I've been keeping a close watch and the drain gets cold enough for water to condense on the surface of the fittings at the evaporator and on down the tubing that leads outside. The outside surface of the evaporator feels really cool but there's no water build up. Everything seems to be draining normal again, but the condensation on the drain tube and the coolness of the evaporator has me kinda gun-shy. Does this sound like a one time stopped up drain problem, or something more complecated?