The fan is actuated as the result of a couple things. First, the temp sensor sends a signal the PCM (computer) telling it what the coolant temp is. Once it reaches a certain temp, the computer sends power through the fan relay which then sends power to the fan motor. If they are running all the time, you could have a bad relay, temp switch, short in the wiring.
Friday, November 19th, 2010 AT 2:26 AM