A refrigeration system comprising: a centrifugal compressor comprising: a case having a suction port and a discharge port ; an impeller mounted for rotation about an impeller axis by a plurality of bearings , the bearings each comprising: an inner race ; an outer race ; and rolling elements between the inner race and outer race; the centrifugal compressor further comprising: a motor coupled to the impeller to drive rotation of the impeller about the impeller axis; the refrigeration system further comprising: a heat rejection heat exchanger coupled to the compressor to receive refrigerant from the discharge port; an expansion device ; a heat absorption heat exchanger coupled to the compressor to deliver refrigerant to the suction port; characterized in that the outer race of each bearing is mounted for radial displacement relative to the case and is surrounded by an associated chamber ; the chambers are coupled to a port on the compressor ; and the refrigeration system further comprises a bearing supply flowpath to said port bypassing the expansion device . a centrifugal compressor comprising: a case having a suction port and a discharge port ; an impeller mounted for rotation about an impeller axis by a plurality of bearings , the bearings each comprising: an inner race ; an outer race ; and rolling elements between the inner race and outer race; a case having a suction port and a discharge port ; an impeller mounted for rotation about an impeller axis by a plurality of bearings , the bearings each comprising: an inner race ; an outer race ; and rolling elements between the inner race and outer race; an inner race ; an outer race ; and rolling elements between the inner race and outer race; the centrifugal compressor further comprising: a motor coupled to the impeller to drive rotation of the impeller about the impeller axis; the refrigeration system further comprising: a heat rejection heat exchanger coupled to the compressor to receive refrigerant from the discharge port; an expansion device ; a heat absorption heat exchanger coupled to the compressor to deliver refrigerant to the suction port; characterized in that the outer race of each bearing is mounted for radial displacement relative to the case and is surrounded by an associated chamber ; the chambers are coupled to a port on the compressor ; and the refrigeration system further comprises a bearing supply flowpath to said port bypassing the expansion device . a motor coupled to the impeller to drive rotation of the impeller about the impeller axis; the refrigeration system further comprising: a heat rejection heat exchanger coupled to the compressor to receive refrigerant from the discharge port; an expansion device ; a heat absorption heat exchanger coupled to the compressor to deliver refrigerant to the suction port; characterized in that the outer race of each bearing is mounted for radial displacement relative to the case and is surrounded by an associated chamber ; the chambers are coupled to a port on the compressor ; and the refrigeration system further comprises a bearing supply flowpath to said port bypassing the expansion device . a heat rejection heat exchanger coupled to the compressor to receive refrigerant from the discharge port; an expansion device ; a heat absorption heat exchanger coupled to the compressor to deliver refrigerant to the suction port; characterized in that the outer race of each bearing is mounted for radial displacement relative to the case and is surrounded by an associated chamber ; the chambers are coupled to a port on the compressor ; and the outer race of each bearing is mounted for radial displacement relative to the case and is surrounded by an associated chamber ; the chambers are coupled to a port on the compressor ; and the refrigeration system further comprises a bearing supply flowpath to said port bypassing the expansion device . <EOS>