A window air conditioner is a room air conditioner. It is the simplest form of air conditioning system and it mounts on windows or walls. The evaporator side is located at the front of the room to cool the space and the condenser side on the outside to reject heat. Window air conditioners are installed and use two air cycles, and the interior of the unit uses a fan to blow air over the evaporator to cool the room. The outside of the window uses a second fan to blow outside air over the condenser and cool it. Air conditioning is divided into two main parts: the inside of your home contains an evaporative coil and filter, and the outside half contains the condensing coil, fan, and compressor.