The Air Conditioner in Animal Crossing is another one which may make some Americans scratch their heads. In the US, we generally know of two types of AC units: central air (which passes cool air through ducts that go through the house) or window units (which install into individual windows and cool a single room).
If you go to Japan or other countries in Asia, you’ll see these wall-mounted units all over the place. They’re known as ductless mini-split air conditioners. They were invented by Mitsubishi Electric and Toshiba in Japan in the late 1950s to accommodate smaller home sizes where it’s not practical or possible to install ductwork for a central AC system. You’re seeing them more and more in the US now because of their efficiency and precision.
The wall-mounted unit is connected to an outdoor unit (which in Animal Crossing is sold seperately as the “Outdoor Air Conditioner”) via a refrigerant line, which spits out heat and humidity and draws in cooled air.
Most units also allow for heating in the winter by reversing the process.
I've been scouring the Web looking for a ductless mini-split AC that looks like the one in Animal Crossing, but their picture is already outdated; most manufacturers don't put the ventilation grille in front of the unit anymore, but force air down vertically.