An HVAC air freshener comprises a cylindrical housing having at least one opening in the wall of the housing along the length of the housing, the housing adapted to be inserted through an opening in a planar portion of an HVAC plenum or ductwork, a magnetic ring encircling and attached to the housing near one end of the housing and adapted to magnetically attach to an exterior planar surface of the plenum or ductwork, and a fragrance cartridge inserted into the housing. The fragrance from the fragrance cartridge escapes from the cartridge through the housing opening and into the plenum or ductwork.