Abstract: A control system for controlling a plurality of compressors by means of fuzzy logic. Control is provided by selecting a combination of available compressors, which may include one or more fixed speed compressors and a variable speed compressor. The controller output signals are responsive to inputs monitoring either the pressures in the system's refrigerant suctions lines, the temperatures of the refrigerated spaces, or where a plurality of evaporators are connected to a set of compressors, the temperature of the coldest refrigerated case, or a combination of the desired suction pressure and temperature of the refrigerated space. The output capacity of the system is chosen based on the degree of membership of each input variable as compared to the total for all inputs.