Abstract: Reversal means for a transverse or cross flow blower is provided which allows for reversal of fluid flow direction without changing impeller rotation direction. In the first embodiment, power means rotate the housing 180.degree. from its initial position, thereby providing for reversal of the fluid flow. In the second embodiment, fluid flow reversal is provided by a pair of inlet and outlet volute walls made up of curved vanes. The vanes are generally elongated and pivotally mounted for rotation about their longitudinal axis by means of linkages connected to a power means. By opening the vanes of one volute wall while closing the vanes of the other, air flow reversal is conveniently accomplished.