Abstract: A housing, for the expansion unit of a cooling system, has a top wall, a bottom wall and end walls; and those walls define a space which accommodates that expansion unit. That housing has a front opening which is filled by an air-distributing transition member; and it has a rear opening that is substantially closed by an air-guiding member. That air-guiding member can support a motor and a pair of multi-vane blowers, or it can be an angular transition for a single blower. That air-guiding member is shorter than the rear opening to provide a short space which can accommodate the supply and return headers of the expansion unit. That air-guiding member can be set in either of two predetermined positions relative to that rear opening to permit the supply and return headers to be located at either end of the housing.