A combine harvester (200) includes a header assembly (210) configured for collecting a crop, a threshing assembly (230) coupled to the header assembly (210) and configured for separating grains of the crop from material other than grain, and a cleaning assembly (240) positioned in association with the threshing assembly (230) and configured for separating the grains from chaff. The cleaning assembly (240) includes a fan assembly (241) having a fan housing (401) with a fan output duct (404) and a fan (402) mounted to the fan housing (401), and one or more cleaning sieves (242, 243). The fan assembly (241) is configured to blow air across the one or more cleaning sieves (242, 243) via the fan output duct (404). The fan output duct (404) includes at least one segmented air deflector (405).
