A controller for a cooling unit compressor having two-phase AC asynchronous motors (K1, K2), the controller comprising mains connection means for connection to a preferably public voltage supply network nominally providing an AC mains voltage between 85 V and 264 V, in particular between 100 V and 230 V, first voltage converter means connected downstream of the mains connection means and serving to generate an intermediate voltage, in particular an intermediate DC voltage, from the AC mains voltage, second voltage converter means (16-1, 16-2) connected downstream of the first voltage converter means and serving to generate an output signal, in particular a temporarily voltage-constant and/or frequency-constant output signal, which is independent from a level and from a mains frequency of the AC mains voltage and which serves to control the cooling unit compressor with an AC voltage of a plurality of different predeterminable voltage levels, voltage detection means being assigned to the mains connection means, which serve to detect the AC mains voltage and whose detector output signal can be evaluated by the second voltage converter means or by controlling means assigned to them in order to generate a maximum value dependent on the mains voltage for a current of the output signal, characterized in that temperature sensor means and operating mode means that can be assigned to a used cooling space of a cooling unit having the cooling unit compressor are assigned to the second voltage converter means in such a manner that in response to a temperature detected by the temperature sensor means being above a threshold, the operating mode means cause the second voltage converter means for generating the output signal to operate on a preferably constant first output AC voltage level with up to a maximum current that corresponds to the maximum current value, and in response to a detected temperature reaching or dropping below the threshold, the operating mode means cause the second voltage converter means for generating the output signal to operate on a preferably constant second output AC voltage level which is lower than the first output AC voltage level, the second voltage converter means for generating the output signal for a first and a second AC asynchronous motor of a cooling unit compressor being configured in such a manner that in a cooling mode, the output signal is generated and outputted only for the first AC asynchronous motor until the temperature reaches or drops below the threshold, and once the temperature reaches or drops below the threshold, the output signal for the second AC asynchronous motor is generated and outputted, and an AC asynchronous motor that is or can be connected to the second voltage converter means being connected or connectable via two phases without any additional sensor lines and/or control lines and having means for generating an auxiliary phase, in particular a capacitor or electronic means for generating an auxiliary phase. first voltage converter means connected downstream of the mains connection means and serving to generate an intermediate voltage, in particular an intermediate DC voltage, from the AC mains voltage, second voltage converter means (16-1, 16-2) connected downstream of the first voltage converter means and serving to generate an output signal, in particular a temporarily voltage-constant and/or frequency-constant output signal, which is independent from a level and from a mains frequency of the AC mains voltage and which serves to control the cooling unit compressor with an AC voltage of a plurality of different predeterminable voltage levels, voltage detection means being assigned to the mains connection means, which serve to detect the AC mains voltage and whose detector output signal can be evaluated by the second voltage converter means or by controlling means assigned to them in order to generate a maximum value dependent on the mains voltage for a current of the output signal, characterized in that temperature sensor means and operating mode means that can be assigned to a used cooling space of a cooling unit having the cooling unit compressor are assigned to the second voltage converter means in such a manner that in response to a temperature detected by the temperature sensor means being above a threshold, the operating mode means cause the second voltage converter means for generating the output signal to operate on a preferably constant first output AC voltage level with up to a maximum current that corresponds to the maximum current value, and in response to a detected temperature reaching or dropping below the threshold, the operating mode means cause the second voltage converter means for generating the output signal to operate on a preferably constant second output AC voltage level which is lower than the first output AC voltage level, the second voltage converter means for generating the output signal for a first and a second AC asynchronous motor of a cooling unit compressor being configured in such a manner that in a cooling mode, the output signal is generated and outputted only for the first AC asynchronous motor until the temperature reaches or drops below the threshold, and once the temperature reaches or drops below the threshold, the output signal for the second AC asynchronous motor is generated and outputted, and an AC asynchronous motor that is or can be connected to the second voltage converter means being connected or connectable via two phases without any additional sensor lines and/or control lines and having means for generating an auxiliary phase, in particular a capacitor or electronic means for generating an auxiliary phase.