A heat dissipating fan includes a housing having an air inlet and an air outlet between which an air passageway is formed. A fixed seat is provided in the air passageway and includes first positioning holes. A magnetically conductive first casing includes a first outer wall, a first annular lip extending radially outward from an end of the first outer wall and having second positioning holes aligned with the first positioning holes, and a first support on the other end of the first outer wall. A second casing includes a second outer wall, a second annular lip extending radially outward from an end of the second outer wall and having third positioning holes aligned with the first positioning holes, and a second support on the other end of the second outer wall. Fasteners extend through the first, second and third positioning holes. A motor is mounted in the first and second casings.