A cooling/heating and power generating device utilizes waste heat from an automobile to produce an auxiliary energy source for driving various accessories such as a cooling/heating apparatus, an electric generator, a super charger and the like. Waste heat is dissipated from the engine by waste gases in an exhaust tube and by a cooling fluid circulating between the engine and a radiator. The inventive cooling/heating and power generating device comprises a heat absorber disposed between the engine and the radiator, a heater mounted on the exhaust tube, and an expansion turbine. A cooling medium is heated in the heat absorber by the cooling fluid of the engine, and in the heater by the waste gases in the exhaust tube. The heated cooling medium drives the expansion turbine thus providing a source of power auxiliary to the engine for driving an electric generator, a super charger, etc. After driving the expansion turbine, the cooling medium is condensed and pumped back to the heat absorber. The cooling medium can also be circulated into a cooling/heating apparatus for cooling or heating the passenger compartment.