Yeah good question, I didn't saw that it has 3 wires. In any case red/black are the input, when connected the fan should run. The yellow wire is the Tachometric Signal wire, when not connected the fan may run fully and I have no clue if the censor on it will work. Another solution could be to use a controller between a four wired fan something as this DC 12V Four Wire Thermostat PWM Fan Speed Controller Module. In any case, the four pins connector can not be used for a fan, I've tested this by connecting a four wire fan on it and installed the Fan2 controller plugging. It won't work, the fan does nothing and the software tells that there is no hardware. So the only way to add a fan to this box is to be inventive by building something by yourself.