Abstract: An air conditioner unit that includes a housing containing a heat exchanger and a centrifugal impeller positioined behind the heat exchanger for drawing comfort air over the exchanger surfaces and returning the air to a comfort zone. A support wall is placed between the heat exchanger and the inlet of the impeller and an orifice is mounted in the wall for directing conditioned air into the fan inlet. A cylindrical shield is also mounted upon the wall and surrounds the orifice. The shield is axially aligned with the impeller and its end face positioned adjacent to the inlet face of the impeller. The axial length of the orifice from the wall is less than that of the surrounding shield so that a wide circular throat is established around the entrance region of the impeller. The velocity of air drawn through the gap between the shield and the impeller is thus reduced within the throat to minimize its adverse effect on the primary air flow entering the orifice.