NOVELTY - The system (1) has expander (42) and pump (44) that are integrally comprised as fluid machine (40). A pulley (12) and belt (14) connect rotating shafts of fluid machine and engine (10) through connection/disconnection clutch (48). An electronic control unit (60) performs connection and disconnection control of clutch. Two shut-off valves (36,38) limit the distribution of working fluid to the expander with respect to connection and disconnection control commands of the clutch by control unit, if abnormality in operation of the clutch is detected with ammeter (54).    USE - System for utilizing waste heat in motor vehicle.    ADVANTAGE - Since the distribution of the working fluid to the expander is limited, when the connection/disconnection clutch does not performs connection operation normally, the over-rotation and the failure of the expander are prevented. The waste heat of the internal combustion engine of vehicle is recovered easily, thus the engine is assisted with driving force efficiently. The noise and the vibration generated by the over-rotation of expander and pump are prevented. The work of the expander forcedly operated with the internal combustion engine is reduced, thus the unnecessary load of the internal combustion engine is reduced. Hence, the fuel consumption of the engine is suppressed, and the deterioration of the fuel consumption in vehicle is prevented. The abnormality in the operation of the connection/disconnection clutch is detected without the need of additional components in the waste heat utilization system, thus the structure of the waste heat utilization system is simplified.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic block diagram of the waste heat utilization system.    Waste heat utilization system (1)    Internal combustion engine (10)    Pulley (12)    Belt (14)    Electromagnetic shut-off valves (36,38)    Fluid machine (40)    Expander (42)    Pump (44)    Connection/disconnection clutch (48)    Ammeter (54)    Electronic control unit (60)