One of the most reasonable reserves to improve the efficiency of ambient air conditioning systems is to enable the operation of refrigeration compressors in close to nominal modes by selecting a rational design refrigeration capacity and its distribution in response to the current thermal load according to the actual variable climatic conditions to provide closed to maximum annual cooling production and to match current conditioning duties at the same time. The approach to improve the efficiency of utilizing the refrigeration capacity of the air conditioning system is based on shearing a rational design refrigeration capacity in two ranges concerning current cooling consumption. The first booster range of ambient air precooling to a certain intermediate threshold temperature is characterized by considerable fluctuations in cooling load, whereas the second range of subsequent subcooling air to a target leaving temperature is characterized by the comparatively stable cooling load. The first booster range of cooling load requires regulation of the cooling capacity, for instance, by the application of a variable speed compressor, whereas the second range of subsequent subcooling air can be covered by the operation of a conventional compressor in a mode closed to a nominal value.