This paper presents a numerical and experimental study of increasing the performance coefficient (COP) of split AC (SAC) by reducing compressor work and increasing cooling capacity. Two phase ejector as an expansion device with a new design of dual evaporator temperature used. numerical methods apply the mathematical model developed in the EES software that is applied. Thermodynamic analysis is carried out to achieve ASHRAE Standard requirements for a minimum SAC with COP application of 3.5. The SAC system is filled with R-290 as a thermal fluid medium. Based on the simulation results a numerical model of the ejector is then produced and installed in a modified SAC system of cooling capacity of at least 9000 BTU/hour. An experimental test was conducted to investigate the actual performance of the ejector and its effect on the performance of the SAC system. The results showed that the two phase ejector with the new design of the dual evaporator temperature system was successful. When compared to standard split air conditioners using capillary tube expansion devices the tested ejector system contributes around 35% of power savings. The COP of the system can reach 5.5 which accounts for 39% of the increase in performance. Use of the constant ejector area COS-SAC dual temperature evaporator system which is intended to be applied for split AC to replace accumulator in standard ejector system has been successful.