A linear fit method of rating residential-type air conditioning systems was evaluated based on performance predictions and laboratory testing of one two-speed matched system and two mixed systems (matched two-speed condensing unit, matched indoor coil blower, and two mixed coil blowers). The individual evaporators and the condensing unit were seperately tested using water heated/cooled condensing/evaporating units over a range of evaporator refrigerant saturation temperatures, evaporator superheats, and liquid refrigerant temperatures.