Air duct outlets having return air passageways that facilitate oscillating air flow

An air duct outlet includes a housing having spaced-apart top and bottom walls, and spaced-apart first and second side walls extending between the top and bottom walls to define an air passageway having an inlet and outlet. A first air return passageway is located adjacent to the first side wall, and diverts a portion of an air stream flowing through the air passageway as the air stream adheres to the first side wall. A second air return passageway is located adjacent to the second side wall, and diverts a portion of an air stream flowing through the air passageway as the air stream adheres to the second side wall. The continuous diversion of portions of an air stream flowing through the air passageway by the first and second air return passageways causes an oscillating, sweeping motion of the air stream as it exits from the air passageway outlet.