Evaporative air conditioning uses evaporation to cool the air. In an evaporative cooler,a pump circulates water from the reservoir on to a cooling pad, which in turn becomes very wet. A fan draws air from outside the unit through the moistened pad. As it passes through the pad the air is cooled by evaporation. The key to effective evaporative cooling is ensuring that each of the cooling pads are completely saturated at all times during operation and that the systems fan & motor are sized and designed to deliver the appropriate airflow for the home.