If you want to save energy, you can just time the quantity of hours need the unit on. It may be the fan blades have gotten bent period. Right away, I'm able to tell you, I advise not in order to purchase a 5000 BTU or 7000 BTU unit. The AC size require depends upon the size of this room you mean to cool. Do keep in mind that ground . AC units need a version of a venting.