A casing for a heat exchange system defines a blower compartment (18), an evaporator compartment (20), and a diffuser (22). The diffuser (22) defines an exit (28) and an entry area in a cutoff plane (30). A vane wall (38) curves inwardly from the diffuser (22) and includes a plurality of parallel vanes (46), (48), (50), and (52). The plurality of vanes (46), (48), (50), and (52) include a first vane (46) and a second vane (48).