Air conditioners are units designed to control the purity, humidity, ventilation, and temperature in a building or vehicle, typically to maintain a cool atmosphere in warm conditions.
Window air conditioners are mounted on an open window. They function by cooling the interior as a fan blows it over the evaporator. On the exterior the heat drawn from the interior is dissipated into the environment as a second fan blows outside air over the condenser. Window air conditioners cool each room separately.