A:Answer Thank you for your interest in this heater. To set a temperature, simply press the (+) or (-) button until it shows on the display. Once you set the desired room temperature, the number will flash to let you know the temperature has been set. At this point, the unit will automatically go back to the current room temperature and you should notice a letter A on the display. This is the indication that the heater is now in Automatic Temperature Control Mode.