In order to improve a method for selecting a frequency converter for a refrigerant compressor unit that includes a refrigerant compressor and an electric drive motor such that the frequency converter is selected in a manner for optimized use, it is proposed that a working state suitable for operation of the refrigerant compressor unit should be selected within an application field of an application graph of the refrigerant compressor, that an operating frequency for this selected working state should be selected, and that a working state operating current value that corresponds to the selected working state and the selected operating frequency should be determined from drive data, for operation of the refrigerant compressor unit.