Sources of broadband noise in FC (forward curved blades) centrifugal fans were studied experimentally using a 0.28‐m‐diameter fan. Strong tangential and axial gradients of mean velocity and static pressure were found in the housing. Very large variations in velocity and velocity fluctuations occurred across the blade passages, from the suction surface to the adjacent pressure surface. Highly separated flow in the blade passages produced a jet‐wake flow pattern with large velocity fluctuations leaving the blades. Measurements on a narrow rotor (0.09 width‐to‐diameter ratio) mounted in a radial diffuser allowed the rotor only noise to be separated from the noise of the complete fan. Both the inlet and discharge rotor noise showed a continuous reduction in level with flow from maximum flow to the stall region. A miniature microphone mounted at various points on the blade surfaces showed a large increase in pressure fluctuations from the leading to the trailing edge of the blades. The fluctuations on the suction surface were much stronger than those on the pressure surface. Several high‐frequency spikes were noted in the pressure surface spectrum. Recommendations for new blade shapes and housing configurations are proposed to reduce the unsteady flows and the related broadband noise.