The air conditioning compressor is usually located outdoors together with the condenser. Most residential air conditioners have their air conditioner compressor combined into a single unit which is sealed. The compressor motor works like a pump which is responsible for moving hot refrigerant gas from indoors of a building through the air ducts and evaporator coil. It then condenses the refrigerant gas causing it to have high pressure and high temperature. The compressor contains a cylinder which has a piston. The piston moves up and down, drawing in the refrigerant gas on the down stoke and then compressing the gas on the upstroke. The AC compressor is not only found in buildings, but also in cars. The function concept in both building and automobile is the same.