Ductless split and mini split air conditioners are made up of two parts, much like a conventional air conditioning system. However, the outdoor compressor and indoor wall-mounted units are connected to each other only by a refrigerant line rather than the more traditional ductwork. That means that mini-split systems are much easier to install in places that don’t already have ductwork or where it wouldn’t be practical to try and fit ducts in. The other main difference between ductless air conditioning units and other types of central air conditioning systems is that the indoor unit mounted on the wall or the ceiling in your room is where the actual cooling takes place. You can adjust the temperature in the room directly from there, giving you a much more refined control over your indoor conditions.