An apparatus for controlling the temperature of a traction energy storage device of an electrically driven motor vehicle, comprising: a traction energy storage device for storing electrical energy which exchanges energy or can exchange energy with an electrical drive train of the motor vehicle; a storage device-side heat exchanger which is in direct thermal contact with the traction energy storage device for heat exchange; a surrounding area-side heat exchanger which is designed to exchange heat with an area surrounding the motor vehicle; and a refrigerant circuit which is designed to guide a refrigerant in a first state of aggregation to the storage device-side heat exchanger and in a second state of aggregation to the surrounding area-side heat exchanger , wherein, in a first operating state of the refrigerant circuit , the first state of aggregation comprises a liquid state of aggregation of the refrigerant, the storage device-side heat exchanger is designed as an evaporator, the second state of aggregation comprises a gaseous state of aggregation of the refrigerant and the surrounding area-side heat exchanger is designed as a condenser, and wherein, in a second operating state of the coolant circuit , the first state of aggregation comprises a gaseous state of aggregation of the refrigerant, the storage device-side heat exchanger is designed as a condenser, the second state of aggregation comprises a liquid state of aggregation of the refrigerant, and the surrounding area-side heat exchanger is designed as an evaporator, characterized in that the apparatus further comprises a control unit which is designed to selectively control the first operating state or the second operating state of the refrigerant circuit depending on the mathematical sign of a difference between a prespecified target temperature and a detected actual temperature of the traction energy storage device . a traction energy storage device for storing electrical energy which exchanges energy or can exchange energy with an electrical drive train of the motor vehicle; a storage device-side heat exchanger which is in direct thermal contact with the traction energy storage device for heat exchange; a surrounding area-side heat exchanger which is designed to exchange heat with an area surrounding the motor vehicle; and a refrigerant circuit which is designed to guide a refrigerant in a first state of aggregation to the storage device-side heat exchanger and in a second state of aggregation to the surrounding area-side heat exchanger , wherein, in a first operating state of the refrigerant circuit , the first state of aggregation comprises a liquid state of aggregation of the refrigerant, the storage device-side heat exchanger is designed as an evaporator, the second state of aggregation comprises a gaseous state of aggregation of the refrigerant and the surrounding area-side heat exchanger is designed as a condenser, and wherein, in a second operating state of the coolant circuit , the first state of aggregation comprises a gaseous state of aggregation of the refrigerant, the storage device-side heat exchanger is designed as a condenser, the second state of aggregation comprises a liquid state of aggregation of the refrigerant, and the surrounding area-side heat exchanger is designed as an evaporator, <EOS>