I cut and paste some intersting diagonsis by Arthur Dalton:
My problem would be the LAW side, I just remembered that my temp control is at the clodest all the time, even though the Air condition is not working, this might have to be the problem?
But Again I would apprciate direction on the sensor..etc
"So, what we have here is two INDIVIDUAL fan circuits that accomplish two different functions, but they do it with the SAME fan MOTOR..
Can we have an aux. fan come on without seeing high engine temps ??
..OF COURSE... it will come on when the a/c system tells it that the high-side pressure is getting up there..nothing to do with engine coolant temps.[this a/c will be low fan, by the way]
Or , can we see a aux fan come on when engine temps start getting up around 105-110 , even with the a/c OFF ???
... Sure.... the coolant temp sensor will activate the Coolant Temp AUX fan CIRCUIT and turn on the AUX fan to AID the radiator with more air to check the high engine temp [ this will be high fan].. This will still be The SAME FAN MOTOR..
So, as you can see , when checking your aux fans, you want to know which CIRCUIT you are checking, because the two circuits have there own relays, sensors, fuses, etc... the only common part they share is the FANS themselves..and that is the tricky part that makes for the confusion..
LOW fan comes on when a/c system is cooling [low temp] and the ambient temps are up in the high thermal load conditions to call for aux fan help...."