An engine cooling system may include a housing forming an enclosed duct having an air intake opening, an air intake door, an exhaust opening, and an exhaust door; at least one heat exchanger positioned within the duct such that ambient air entering the air intake opening flows through the duct to contact the at least one heat exchanger and exits the duct through the exhaust opening; and a controller connected to vary a degree that one or both of the air intake door and exhaust door is open to modulate a mass flow rate of ambient air contacting the at least one heat exchanger to vary a heat transfer from the at least one heat exchanger to the ambient air in the duct to maintain a temperature of a fluid within the at least one heat exchanger within a preferred temperature range.