A system comprising: a first display case; a second display case; a first compressor having a first inlet and a first outlet; a second compressor being a sumpless compressor and having a second inlet and a second outlet, the second compressor providing working fluid discharged from the second outlet to the first inlet of the first compressor; a first heat exchanger disposed upstream of the second compressor and providing working fluid to the second compressor, the first heat exchanger and the second compressor being disposed within the first display case; a second heat exchanger disposed upstream of the first compressor and providing working fluid to the first compressor, the second heat exchanger being a medium-temperature evaporator disposed within the second display case that is operated as a refrigerator; a bypass passageway that extends from a suction line of the second compressor at a location between the first heat exchanger and the second compressor to a discharge line of the second compressor; a bypass valve disposed along the bypass passageway and movable between an open position in which fluid is allowed to flow through the bypass passageway and a closed position in which fluid is restricted from flowing through the bypass passageway; and a control module in communication with, and configured to control operation of, the first and second compressors (12, 14) and the bypass valve; wherein: the control module controls the first heat exchanger to operate as a low-temperature evaporator and controls the first display case to operate as a freezer by controlling the bypass valve to move to the closed position while controlling the second compressor to operate and turn on; and the control module controls the first heat exchanger to operate as another medium-temperature evaporator and controls the first display case to operate as another refrigerator by controlling the bypass valve to move to the open position while controlling the second compressor to turn off. a first display case; a second display case; a first compressor having a first inlet and a first outlet; a second compressor being a sumpless compressor and having a second inlet and a second outlet, the second compressor providing working fluid discharged from the second outlet to the first inlet of the first compressor; a first heat exchanger disposed upstream of the second compressor and providing working fluid to the second compressor, the first heat exchanger and the second compressor being disposed within the first display case; a second heat exchanger disposed upstream of the first compressor and providing working fluid to the first compressor, the second heat exchanger being a medium-temperature evaporator disposed within the second display case that is operated as a refrigerator; a bypass passageway that extends from a suction line of the second compressor at a location between the first heat exchanger and the second compressor to a discharge line of the second compressor; a bypass valve disposed along the bypass passageway and movable between an open position in which fluid is allowed to flow through the bypass passageway and a closed position in which fluid is restricted from flowing through the bypass passageway; and a control module in communication with, and configured to control operation of, the first and second compressors (12, 14) and the bypass valve; wherein: the control module controls the first heat exchanger to operate as a low-temperature evaporator and controls the first display case to operate as a freezer by controlling the bypass valve to move to the closed position while controlling the second compressor to operate and turn on; and the control module controls the first heat exchanger to operate as another medium-temperature evaporator and controls the first display case to operate as another refrigerator by controlling the bypass valve to move to the open position while controlling the second compressor to turn off. the control module controls the first heat exchanger to operate as a low-temperature evaporator and controls the first display case to operate as a freezer by controlling the bypass valve to move to the closed position while controlling the second compressor to operate and turn on; and the control module controls the first heat exchanger to operate as another medium-temperature evaporator and controls the first display case to operate as another refrigerator by controlling the bypass valve to move to the open position while controlling the second compressor to turn off.