This invention provides a freezer/refrigerator system which has a compressor driven by an engine of a vehicle to equally supply a refrigerant under pressure to a cooler unit and a freezer/refrigerator unit. An electromagnetic valve is disposed in a refrigerant inlet pipe of the cooler unit, while a constant-pressure expansion valve which is opened at a given pressure corresponding to a proper vaporizing temperature of the refrigerant is disposed at the refrigerant inlet pipe of the freezer/refrigerator unit. A control circuit supplies a control signal to the electromagnetic valve which is opened for 1 minute and closed for 15 seconds. The refrigerant is alternately supplied to the cooler unit and the freezer/refrigerator unit upon opening/closing of the constant-pressure expansion valve in accordance with changes in the pressure of the refrigerant.