In this study, a dual evaporator ejector system (DEES) was experimentally investigated in order to determine the effective cooling capacities depending on entrainment ratios (ER). An experimental performance analysis was conducted on the system to assess the range of entrainment ratio in which both evaporators can operate effectively. To this end, superheating temperatures, compressor isentropic efficiencies, compression ratios, pressures at the ejector outlet, cooling capacities, and throttling ratios (for TXV#1) were analysed in association with entrainment ratio values to determine the upper and lower limits for effective operating conditions. The results show that the compressor isentropic efficiency drops with the increase of entrainment ratio. Isentropic efficiency was calculated as 0.69 and 0.71 for R134a and R456A, respectively, when the entrainment ratio was above 0.8. Special attention was paid to the superheating temperatures of the second evaporator of the system. When the entrainment ratio was higher than 0.8, the superheating temperatures was found to be 35 °C for R134a and 30 °C for R456A. Because an expansion device was utilized before the evaporator#2, very low evaporation pressures were obtained in the evaporator#2; but this caused an excessive increase in the superheating temperatures. It can be asserted that both evaporators can be operated at the desired cooling capacities, when the entrainment ratio is between 0.4 and 0.8. Finally, although the cooling performance of R134a was 10% higher than that of R456A, the coefficient of performance (COP) of R456A was higher than R134a.