Setup of a portable ac conditioner is typically simple and painless. The biggest thing to keep in mind is that the heat which an air conditioner removes from the room's air needs to be vented out somewhere. If it’s simply allowed to escape back into the room, the room will cool very slowly, or one side may be warm while another is cool. Because of this, a portable AC unit usually comes with a venting kit that fits in the window and accommodates a flexible hose that runs from the unit. Hot air is vented through this hose to the outdoors.