of fig3 is similar to the control of compressor 40 of fig2 while the control of compressors 42 and 42 39 of fig3 is similar to the control of compressor 42 of fig2 assuming that the compressors are similarly sized it will be seen that the refrigerant flow is reduced by 1 3 capacity by de energizing compressor 40 at low loads blower motor 32 is reduced 1 3 in speed by being switched from four to six pole operation thus it may be summarized that a 1 3 reduction in blower motor speed and air flow is also accompanied by a 1 3 reduction in the number of tubes 82 in the evaporator heat exchanger being supplied in the embodiment of fig2 the reduction in active tubes and air flow at the indoor heat exchanger is 1 2 unlike conventional modulation means this invention pertains to a unique combination of evaporator circuit control and air flow control which can permit the evaporator to continue to operate at reduced loads at essentially the same evaporator temperatures as under full load thus in conventional systems using only air flow modulation the evaporator temperature drops with reduced air flow thereby causing the evaporator to frost up under appropriate humidity conditions in other conventional systems wherein some intertwined or interspersed circuits are deactivated without commensurate air flow reduction the evaporator temperature rises thereby increasing the sensible heat ratio of the evaporator which may be defined as the.