Abstract: An agricultural harvester (100) has a chassis (106) supported on a plurality of wheels (110) for travel over the ground; a harvesting implement (104) supported on the front of the chassis (106); an internal combustion engine (108) disposed on the chassis (106) behind the harvesting implement (104); a radiator (112) coupled to the internal combustion engine (108) to transfer heat from engine coolant to ambient air; a fan (109) disposed to draw a flow of cooling air through the radiator having a first flow rate; and a conduit (114) configured to conduct substantially the entire first flow rate of air to the radiator (112). The conduit defines a lower air-impermeable enclosure surrounding the inlet of the radiator fixed to an upper enclosure comprising a plurality of screen walls for passing substantially the entire flow of cooling air therethrough.