A molded through-flow motor assembly has a motor housing, including a cup portion and a flange portion. The flange portion includes a plurality of ramp surfaces extending outwardly therefrom. The cup portion has a field retaining wall and guide rib extending inwardly therefrom on opposite sides of the housing. A diffuser plate is provided having a plurality of scalloped ramp surfaces on a first side thereof adjacent to a plurality of air inlet apertures which open into air chambers on the second side thereof. The field and armature portions of a motor assembly are mounted in the motor housing and the diffuser plate is fitted to the flange portion of the housing such that the ramp surfaces abut one another to form a continuous ramp surface from each air inlet aperture into the air chambers. A rotating fan member is mounted to the armature shaft and is housed within a shroud cover fitted to the motor housing. In operation, air is directed through the shroud cover by the rotating fan and into the air chambers by way of the air inlet apertures and ramp surfaces. Air is directed over the field and armature assemblies and out through vent cutouts in the cup portion of the housing.