If they fail to come on, your problem will be the fan speed resistor, this cuts it down from 12v to 6v. This resistor, believe it or not, is situated behind the radio on the passenger side. This can be accessed by removing the side panel.
The sensor that you started this thread about on the left hand side of the engine, as Lee said, is used purely as a plug and no wires will have ever gone to this on your car.
Should you need more info, PM me and I'll send you my number.
Andrew
