In this study, the effects of ratios of outdoor and return air volume flow rates, the temperatures of mixture air, return air, and cooling coil outlet on the cooling coil capacity and exergy destruction and exergetic efficiency are experimentally investigated. During the experiments, the ratio of outdoor air volume flow rate on the total air volume flow rate is changed from 30% to 70% while keeping the total air volume flow rate as 12 m³/h, specific humidity as 0,0054 kg.w.vapor/kg.dry air and outdoor air dry-bulb temperature as 35 °C. A computer code is developed to calculate the cooling coil capacity, exergy destructions and exergetic efficiency. The analyses including the first and second law of thermodynamics are carried out by Engineering Equation Solver (EES-V8.172-3D) which is commonly used in the analysis of thermal systems and contains thermo-physical properties of the fluids in its library. As the ratio of outdoor air volume flow rate on the total air volume flow rate increases, the heat transfer from the air flowing through the cooling coil and amount of exergy destroyed in the cooling coil increases but the exergetic efficiency of the cooling coil decreases.