Abstract: A method and system for reducing windage losses in compressor motors is provided. The compressor motor is cooled by circulating refrigerant from a closed refrigerant loop incorporating the compressor. A pumping device coupled to a liquid expander in the closed refrigerant loop circulates refrigerant through the motor cavity and produces a motor cavity pressure lower than evaporating pressure. The lower pressure in the motor cavity reduces the density of the gasses in the motor cavity, resulting in reduced windage losses of the motor. Additionally, the pumping device is powered by the recovered liquid expansion energy between the condenser and the evaporator.