Abstract: A forwardly-opening scoop is positioned at the upper rear of a snowplow or the like, and a downwardly directed duct portion communicates with it to direct air downwardly along the vertical rear wall of the truck. The device has multiple air outlets, to distribute the air to different areas, to maximize the cleaning effect. Preferably, the device extends down to cover the full height of the rear wall, and includes an air outlet at the bottom edge so that tail/brake lights are also washed by air. A reflective checkerboard preferably is displayed on the device.