The described embodiments relate generally to cooling fans and more specifically to a method for balancing an impeller assembly included in a cooling fan. In one embodiment, a balancing ring with an asymmetric shape can be included in an impeller assembly and rotated to correct an unbalance in the impeller assembly. In another embodiment, a balancing ring assembly can be provided including an inner balancing ring and an outer balancing ring. The size and shape of the inner balancing ring can be modified to better correct any unbalance in the impeller assembly.