Air conditioner has been one of the main necessities for mankind, especially for people living in warm climate countries such as Indonesia. The need for air conditioner itself functions for the comfort of users and also operating functions of certain equipment. Due to global warming, increase in the temperature of the Earth forces greater energy consumption of air conditioner to reach the required room temperature requested by the user. This increase in energy consumption has been the focus of the Indonesian government in finding solutions to help reduce energy consumption from non-renewable energy power plants while still fulfilling societies demand. One solution is applying energy labelling for air conditioners using Energy Efficiency Ratio (EER) as a parameter. In order to calculate the EER of air conditioners, a controlled room environment is needed, thus the reason of creating the Psychrometric Chamber. One of the required data to calculate EER is air flow from evaporator. Airflow measurement can be calculated from pressure different between inlet and outlet of divergent nozzle. Pressure transmitter is the instrument that can measure the pressure different. The result of this research is finished construction of an air flow measurement device which consist of nozzle box, perforated plate, nozzle plate, divergent nozzle, pressure transmitter, flexible duct, and blower.