Thanks for setting me straight, Alan... yet again. I was under the impression that the two fans operated independently but I cannot tell you exactly why. Probably from reading threads about others' fan problems and not recognizing incorrect information. You are certainly right about it not making sense that side-by-side fans would operate independently - but OTOH I am still trying to make sense of having TWO windshield washer systems.

I know the after-running doesn't work ever because it didn't run last year at a 100*F DE day after pulling into the paddock due to an over-heat warning... and that's GOT to be hot enough to get the fan to run. So, is it the fan controller Mark posted that would need replacement to regain after-running? Or is in the intake temp sensor you mentioned?

Very nice that you have been working on a baseline-and-repair manual!! You're the man for that! I will be happy to pay (very) good money for one! I realized recently that I have been chasing my tail on a couple of suspected faults, and that's when this idea came to me...

 

Test the operation by bypassing the thermal switch on top of the intake as I noted - its not really about coolant temp only intake top temp.. for it to trigger you need to shutdown right after a high load run at high engine temp and high ambient temp. Even with a slightly overheated engine it is possible (though unlikely) that it wouldn't come on... without sufficient ambient temps, engine load & heat soak.

However come on down to Phoenix and you will definitely find conditions to trigger it... But from what you noted it sounds very suspect - it may be as simple as replacing the switch - I think its rather unlikely you need a new fan controller... quick test for it...

Alan

 

When I pull the rad temp sensor (at the fet bottom corner of hte rad), only the primary (passanger side) fan kicks in. If I read the above posts right, both should come on at full speed, right?

 

"When I pull the rad temp sensor (at the fet bottom corner of hte rad), only the primary (passanger side) fan kicks in. If I read the above posts right, both should come on at full speed, right? "

If you are jumpering the connections in the radiator sensor harness plug, both fans should run at full speed (ignition on).

If only one runs, check the fuses and the red wires on the battery positive post. Swap fan connectors as a last check.