A model of a Dehumidifier-Integrated Air Conditioner (DHIAC) with the ability to control air temperature and humidity precisely at the same time has been developed by our research team. In this research, the operation of DHIAC in hot and humid climate conditions for one year was simulated to evaluate the device's performance. The gray box simulation method, combining theory and experiment, gives high accuracy, and a convincing argument is selected for the application. The simulation program is built on Matlab software based on a system of equations to simulate the change of temperature and humidity parameters of the air-conditioned space and regional weather data for a long time. It allows the evaluation of the equipment's operating efficiency in a one-year cycle. Simulation results show that DHIAC can control air temperature and humidity parameters according to national standards with high accuracy. The maximum error of air temperature and humidity compared to the set value is 2.7%. The average EEF energy efficiency factor for the whole year is 2.2. Maximum process time is 1095 s in summer and 607 s in winter. This DHIAC can provide a comfortable environment for people with low energy consumption.