In this study, air distribution, indoor air quality based on carbon dioxide, and thermal comfort are investigated numerically by using a breathing thermal manikin model in an office room that is heated by a split-type air conditioner. The effect of ventilation parameters like inlet temperature and inlet velocity on thermal comfort and CO2 removal is also examined. Measurements of one of the faculty member offices of Bursa Uludag University (Faculty of Engineering, Department of Mechanical Engineering) are used for office room geometry. The airflow in the room is considered threedimensional, transient, turbulent, multiphase, and compressible. The standard k-epsilon turbulence model is used with scalable wall function. According to the results of this study, the average temperature difference between the warmest and coolest cases is lower than the difference in the blowing temperatures of these cases. Also, according to predicted mean vote (PMV) results, despite different inlet velocities and temperatures, the same comfort levels can be obtained in different cases. Different amounts of CO2 values were also obtained in all cases and it is considered that there is no obvious pattern between examined blowing parameters with CO2 amount in the room.