Why isn't my AC draining water?

If your air conditioner is not draining any water, it usually points to one of a few common scenarios, ranging from completely normal operation to a troublesome blockage. First, if the outdoor weather is cool, dry, or low in humidity, the air conditioning system may simply not be pulling much moisture out of the air, resulting in little to no condensation production in the drain pan. Second, and much more commonly, a lack of drainage is caused by a physical clog in the PVC condensate drain line due to an accumulation of algae, mold, dust, and sludge, which blocks the water from escaping and causes it to back up into the indoor overflow pan. Third, a disconnected or broken drain pipe, a malfunctioning condensate pump, or a frozen evaporator coil that temporarily stops melting ice can also prevent water from flowing through the drainage system properly.