The size of your apartment will be one of the most important factors in which type of air conditioner is most suitable. A studio apartment and a three bedroom will have very different cooling requirements. If you only need to cool a studio or perhaps just one room of a larger apartment, smaller systems like window units or portable units may be suitable. A ductless/mini split units will generally be the best option for larger spaces.
If you’re renting or want to avoid serious wall modification, this is the way to go.
The advantage with window units is that all the important parts—the compressor, condenser, expansion valve/coil, etc.—are all in one big box. The installation of these is much simpler and they’re very portable. Window units provide the most cost-effective and painless solution to cooling a single room. The units are relatively cheap and they have a lot of cooling power.
The simplest non-window based option is a portable A/C unit. These are devices that usually sit on the floor near a window. Hoses will carry air inside and out through a window. Typically, these units will come with adjustable hose frames to place in the window that keep them in place. Technically, all the parts are physically in one box, but you’ll still need a connection to the outside world for them to function.
Portable units are for those who absolutely can’t use a window unit and aren’t able to do any wall modifications. As Consumer Reports points out, they’re costly and not very efficient in general. A similarly-sized window unit will cool better than its portable counterpart.
Split units consist of two parts: the indoor component that you can mount on a wall, and the outdoor component that sits cozily next to your home. A “ductless” means that you don’t need to have a complex system of ducts installed throughout your entire home. You will, however, need hoses running from the inside of the room you want to cool to the outside condenser unit.
Split units are comparatively simple to install as they just require drilling holes in a wall and running wires through it. A split system is a great option if you live in a hot region and need to cool a large area inside your home. Their cooling power is among the closest you can get to real central air without tearing apart all your walls and ceilings to install. The two main disadvantages here is that these units will be among the more expensive you can find, and you can’t move them from room to room like you can with a window or portable unit. You will also still need multiple units to cool separate rooms