Conical diffusers with or without conical center bodies can improve air moving performance by up to 21% at no increase in power. Embodiments coupled with electronically commutated motors (ECMs) showed additional reductions to condenser fan power of approximately 25%. A strip member, such as open cell foam can be applied as a liner to the interior walls of a condenser housing adjacent to the wall surface where the rotating blades sweep against. The porous edge can also be used with the trailing edge and/or tip edge of the blades. These members can both improve air flow by reducing dead air spacing between the rotating blade tips and the interior walls of the condenser housing, as well as lower undesirable noise sound emissions.