The invention concerns an air blower (20) in­cluding a centrifugal fan (220) which is driven by an electric motor (210). The blower (20) has a two-part blower housing (22, 24) comprising an upper housing (22) which encloses the motor (210) beneath the motor cap (230) and a lower housing (24). The centrifugal fan (220) is disposed in the chamber between the upper and lower housings (22, 24). The plenum (54) around the fan (220) leads to an outlet (161) from the blower (20). An intake shield (120) extends across and blocks undesired entrance of objects into the inlet opening (86) in the bottom (84) of the lower housing (24). The blower (20) may be seated on a lid (180) across an opening in it. An adapter (140) in the lid (180) re­ceives the intake shield (120) and has its own air in­let (146) to the blower (20). The orientation of the blower (120) with respect to the lid (180) is rotata­ble. Cooperating flanges (132, 166) on the blower and the adapter hold the blower to the lid (180) at two ro­tative locations and a button latch arrangement (190) (Fig. 12) latches the blower (20) at each of the two arrangements. Between the two latched orientations, the blower (20) may be lifted free of the lid (180).