What causes the cooling fan to run at high RPMs in a 1998 mercury mystique? I put a new thermostat in the engine and now the fan runs constantly and will not shut off. Please help me! Need advice! Do not know what to do in order to fix this problem
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.