Electric Fans Not Turning On

rbreith

Member
Oct 15, 2013
62
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I installed electric fans into my 89 mustang with the probe thermo sensor in the bottom of the radiator near the outlet to the engine. I ran the car and it just got really hot without the fans ever turning on. I have the switch set to turn on at 180 degrees right now to check it and its not working. I however know that the wiring is correct due to the fact that I also wired it for manual on with a switch and it works fine. do I need to move the thermo sensor and if so where. Also how good do the probe in radiator sensors work vs a thread in
 
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The probe should be installed about an inch below the upper radiator hose. To test the fan, you can either turn on the A/C if you installed the A/C bypass wire or bridge the temp sensor connections with a wire. What controller are you using?
 
The probe should be installed about an inch below the upper radiator hose. To test the fan, you can either turn on the A/C if you installed the A/C bypass wire or bridge the temp sensor connections with a wire. What controller are you using?

That may work for a switch type sensor, it depends on if it trips open or closed when it reaches the set point.
It won't work for a thermistor like the ECT or water temp gauge sender..
Some time spent with the sensor connected only to a heat source and ohmmeter will be needed to determine what type of sensor is being used.
 
x4 on moving the probe. People have had good success with push in probe type sensors when installed correctly while there's no doubt the thread in is better. Set the fan to come on at a cooler temp until you get it all dialed in.