A central air conditioner is like a giant refrigerator for your house. In fact, it employs the same types of components, materials, and systems as a refrigerator, including a refrigerant that changes from liquid to gas and back to liquid as it travels through a system of tubes and coils or fins that collect and give off heat. As it goes through this cycle, it gathers heat from one place and transfers it to another. At the same time, it creates cold (the absence of heat) in one place and delivers that chill to another.
A central air conditioner runs on electricity. During summer months, when it runs a lot, it can consume a lot of energy, so the efficiency of the air conditioner can be a very important feature.
A ductless mini-split air conditioner works like a regular central air conditioner but without the ducts. The indoor unit blows warm air from your home over cold evaporator coils. The refrigerant running through these coils absorbs the heat from the air and brings it the outside unit where the refrigerant dumps all the heat it pulled from your home’s air. Most ductless mini-split systems are heat pumps. That means they can both heat and cool your home, eliminating the need for a separate heater.
Advantages of the ductless system include smaller size and flexibility for zoning or heating and cooling individual rooms. The inside wall space required is significantly reduced. Also, the compressor and heat exchanger can be located farther away from the inside space, rather than merely on the other side of the same unit as in a window air conditioner.
Window unit air conditioners are installed in an open window. The interior air is cooled 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.
A window unit is small and is designed to cool just a small space…not an entire house. It is no different from other air conditioners in its operation, but it is smaller and confined to a small space. They are also portable in the sense that they can be installed in any room that has an adequately sized window.