In the paper, based on MS Thesis by Richtr, 2000, the authors describe CFD modeling of a computer room with regard to thermal comfort of workers. The room was equipped with an additional A/C and people felt uncomfortable in certain places after the installation. As input data for CFD simulation, individual heat loads measured on computers and monitors were used. Different scenarios of adjustable vanes of the A/C diffuser and further modifications were studied. Based on the results of velocity and temperature fields, a solution was suggested to improve the both fields in respect to obtain a better thermal comfort in the room.