An air conditioner has a flow directing vent comprised of slanted vanes. The vent is driven by a drive mechanism which oscillates the vent about an axis. The drive mechanism includes a motor driven shaft which rotates continuously in one direction, and a mechanism for converting such continuous rotation into oscillation of the vent. The drive connection between the vent and drive mechanism can be manually disconnected by axial displacement of the vent, to enable the rotational position of the vent to be adjusted relative to the drive mechanism.