The ac unit in my basement has water leaking from the very bottom of it. There is a small pool of water at the bottom of the casing of the fan on the inside at the very bottom. The unit cools the house a bit but it is still 4-5 degrees warmer than what the thermostat is set for. What do I do?

MW, June 2010

Air conditioners remove humidity in addition to cooling the air. That removed water has to go somewhere -- usually out a pipe or tube to a floor drain or the like. Most commonly this drain pipe becomes plugged with debris over time and the water backs up and overflows into the furnace. Check this drain pipe (you may have to remove it to do so). There is supposed to be a water-trap (U-shaped section) in the pipe to prevent the loss of cold air and this is the most likely location for obstruction. If this is not the cause, the catch tray under the cooling coils in the furnace could be damaged, and that's usually a job for a professional.

SystemDude, July 2010