Portable AC units suck. The problem with them is simple physics. With a window mount or central air, the hot exhaust is cooled from outside air and released to outside air. With a portable unit, the hot exhaust air is cooled from internal house air and released out side. But where does it get this internal air to cool? It sucks in warm humid air from somewhere in the house into the very room you are trying to cool thus mostly nullifying the cooling you were trying to accomplish. All this at the cost of the unit, lugging it upstairs, electricity (a lot), and noise (a lot).
