Computational Fluid Dynamics (CFD) is today an important tool in the design process of fuel and energy efficient vehicles. Under-hood management is one of the fields where CFD has proven itself to be useful for cost-efficient development of products.Multiple Reference Frame (MRF) method is the most common used tool in the industry for modeling rotating parts. In previous papers, the modeling strategy with MRF has been documented for open fans and showed high capability to predict fan performance. One of the open points of this proposed method has been its applicability to closed fans (ring fans), as industry experience and discussions has indicated previous conclusions of open fans and MRF modeling may not apply across ranges of fan designs. This paper investigates the MRF method for a closed fan with U-shroud and analyzes several aspect of the modeling strategy.The finding of this paper is that the MRF method predicts fan performance for closed fans with equal accuracy as it does for open fans. This paper will also present sensitivity to the user-specification of the method (MRF Domain) and impact of the frozen rotor position of the rotor.