The part(s) or condition(s) listed below for the symptom Air conditioner leaking water are ordered from most likely to least likely to occur. Check or test each item, starting with the items at the top of the page.
If the window or through-wall air conditioner is leaking water from the front, this indicates that the air conditioner is leaning too far forward. The air conditioner is designed to expel the condensate water from the back of the unit. Because of this, the air conditioner must be installed so that it leans back on a 1-2 degree angle.
Most window air conditioners have a polystyrene foam tray in the bottom that collects the condensed water from the evaporator. If the air conditioner is correctly tilted downward, towards the outside, the water will run through a trough or channel to the back of the unit. From there the water is usually picked up by a slinger fan blade (a fan with a ring around the outside of the blades) and projected at the condenser coil. The water along with the outside air removes the heat from the condenser coil. If the unit doesn't have a slinger fan, or there is excessive water in the rear tray, the water will run out of a drain hole in the bottom frame. If the trough which runs from the front to the back of the unit, or the drain hole at the rear of the unit, is clogged, water can back up and leak into the home.