Abstract: An apparatus for injecting air freshener or other airborn vapor into the air of a building, mounts to the side of a manifold or other air passageway, which is part of the building air conditioning or heating system. A solid, liquid-saturated dispersant cylinder is ultimately inserted into the passageway and removed from the passageway into a substantially sealed container by means of an electric motor drive which is controlled by a microprocessor-driven control system. The programmable control system is set to introduce the solid dispersant into the air passageway at selectable times of the day and for a set duration, but may be overridden manually in the event a party is to be held, etc.