Left side of the engine bay towards the front of the car. It's mounted in the coolant pipe. Just up-plug it and by making a small jumper lead with two spade terminals, connect the two ends together. With the ignition on, your fans will run continuously. You should get it replaced though. I think Rich has his old one which he replaced jus tto have it cut in at a lower temp. The rubber bit might be crappy though.
Sorry I didn't mean to suggest that they were related.. just if I leave it idling the fans never come on now! Wouldn't know how to jump that connection either! (where would it even be?)