An experimental work on using a new technique of thermal energy storage system with conventional air conditioning (AC) unit to raise its performance is presented. The technique is based on integrating plates of phase change material (PCM) with the condenser of the AC unit. The PCM plates use their cold storage energy during the night to increase the cooling performance of the AC unit during the next daytime. An experimental test rig for the PCM thermal storage plates is constructed in two configurations; horizontal and vertical plates. The experimental study is performed during the discharging of the charged cold storage energy at night to the AC unit at day. The effect of the PCM plates configurations and the velocity and temperature of the air inlet to the PCM plates on the discharging process and AC unit performance is presented. The results show that the coefficient of performance (COP) of the AC unit with PCM plates is greater than its COP without using PCM plates. At the initial period of the process, the outlet air temperature from the vertical PCM plates is smaller than that of the horizontal plates and after a certain period, the situation is reversed. Using PCM plates heat exchanger decreases the condenser pressure and increasing the evaporator cooling capacity. At inlet air velocity and temperature 0.96 m/s and 45 degrees C, using vertical and horizontal PCM plates decreases the consumed power of the AC unit by about 9.8% and 11.2%, respectively compared with AC unit without PCM plates. (C) 2018 Elsevier B.V. All rights reserved.