A Central Air Conditioner uses the same control thermostat as your home’s heating system. The air conditioner unit itself is outside. It contains the compressor and condenser-the hot side of the unit, and the cold side -the evaporator and a fan that blows air over the chilled coils and into the room. A fan vents hot air coming off the compressed refrigerant to the outdoors. Keep up on maintenance and air conditioning repair and your unit will give you many years of wonderful cool air.