zimstang, it doesn't override the normal fan operation, but with the switch you can turn the car off at the track and turn the fan on to help cool. every single person that's serious about performance (esp. drag as it cuts down wait time) ends up wiring such a switch. the computer does it's job fine, but that's not what we're talking about even. a 160 ro 180 deg thermo along with this and water wetter will cut cool down time in half.