In this study, the combination of a vapor compression cycle with a phase change material (PCM) storage tank has been assessed experimentally during the hottest day based on Tehran city climatic conditions. The temperature conditions for outdoor (condenser, compressor, etc.) and indoor (evaporator) air conditioning (AC) units are provided with the help of two separate test chambers and a controller system. The desired system has been surveyed based on two scenarios. In each scenario, the system is evaluated for the conventional AC system (with no PCM involved) and the AC plus PCM unit (conventional AC + PCM storage tank). Based on scenario 1 operating strategy, the results show that adding the PCM tank diminishes the total COP and total accessible cooling load during 24 hours. Whereas the AC plus PCM system's performance improves during on-peak hours (12:00 – 19:00) compared to the conventional AC system (with no PCM involved). Based on scenario 2 operating strategy, adding the PCM storage tank to the conventional AC unit increases total electric energy consumption over 24 hours. While it leads to reducing electric energy consumption during on-peak hours by about 84.5 %.