if your car is overheating the chances are that you either have
a) the thermal switch attached to your engine is faulty and not sending a signel to your cars computer telling your cooling fan to come on
( this can also cause your fan to be on constantly)
b) the circuit on your engines computer which recieves the "turn on " information is faulty and is not sending the information it recieves to the cooling fan
or
c) your cooling fan motor has burned out or shorted out in some way
john gibson
January 2010