Split-type air conditioner (A/C) is widely used in commercial and residential buildings. Enhancement on the performance of this A/C can result in significant energy savings. An ejector as expansion device can be applied on the split-type A/C for COP improvement. This paper presents numerical and experimental investigation on the system performance of a split-type A/C using an ejector as an expansion device compared to standard cycle (SC). The present study introduces a novel ejector cycle based on modification of standard ejector cycle. The standard ejector cycle (SEC) uses a separator that has an inlet and two outlets, whereas the modified ejector cycle (MEC), the separator has only an inlet and an outlet applied in the system. In the numerical study, the conservation equations of mass, momentum and energy were applied. The numerical results showed that the motive nozzle and mixing chamber diameters of 1.1 and 2.5 mm, respectively give optimum COP improvement on the system. These results were further confirmed experimentally and showed that the modified ejector cycle (MEC) has increased in COP of 4.17, 11.14 and 13.78% at the ambient temperature of 30,35 and 40 degrees C, respectively. Comparing the numerical and experimental results of MEC showed poor agreement due to high difference in their entrainment ratio. (C) 2014 Elsevier B.V. All rights reserved.