A variable orifice flow device controls the flow of a fluid between a volute casing and a compressor motor casing in a compressor. The variable orifice flow device may be a shuttling valve, with positions controlled by, for example, valves controlling the flow of the fluid into a space opposite a side within the shuttling valve assembly. The variable orifice flow device may have one or more orifices through which a fluid can enter the compressor motor casing, and the surface area of the orifices may be controlled by the position of the shuttling valve.