A refrigeration system comprising: a centrifugal compressor comprising: a case having a suction port and a discharge port; an impeller (162, 164) mounted for rotation about an impeller axis by a plurality of bearings (80, 82), 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 (162, 164) mounted for rotation about an impeller axis by a plurality of bearings (80, 82), 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 (162, 164) mounted for rotation about an impeller axis by a plurality of bearings (80, 82), 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.