Thermostatically Controlled Electric Fan

bobfake

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Hi all,

the SUper Bee was running pretty hot (per the temp gauge) while sitting in some bumber to bumber traffic. I bought a 12" thermostatically controlled fan which I am installing as a push through. I have most of the wiring completed, but I have a question...

They sent me a temperature sensor to install which I would connect the fan to so it comes on at 180 degrees. My question is, can I splice into the existing wire from the existing temperature sending unit to the dash temp gauge to control the fans? I don't want to have to install another sending unit somewhere to control the fans.

Thanks!!
Bob
 

Don67Satellite

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In a word, nope. That sender with the electric fan is made to turn the fan on at 180 degrees, and off at 165 or whatever it is rated for. The temp sender for your dash gauge is not made for that. You'll have to find another port in the WP housing or somewhere else to install the sender.
 

Jerry Hall

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No, I don't think so. The sensors I have seen go in the radiator fins and connect to a relay that switches 12V to operate the fan.
 

Jerry Hall

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20220915_154733.jpg

Here is a setup recently removed from a car to go with something different.
 

Don67Satellite

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You have another option if you have no other available ports for the sender, is to manually turn the fan on/off when you need. My pusher fan was hooked up with a relay per this diagram when I had FiTech fuel injection. Since removing the EFI, the yellow wire in the diagram, now goes to a grounded toggle switch.

Screen Shot 2022-05-03 at 5.30.02 PM.png
 

RJRENTON

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Hi all,

the SUper Bee was running pretty hot (per the temp gauge) while sitting in some bumber to bumber traffic. I bought a 12" thermostatically controlled fan which I am installing as a push through. I have most of the wiring completed, but I have a question...

They sent me a temperature sensor to install which I would connect the fan to so it comes on at 180 degrees. My question is, can I splice into the existing wire from the existing temperature sending unit to the dash temp gauge to control the fans? I don't want to have to install another sending unit somewhere to control the fans.

Thanks!!
Bob
Short answer......no. The sensor that operates the dash board instrument is a resistor that changes its value (DECREASES) its resistance as coolant temperature increases. The dash mounted instrument is a simple volt meter calibrated to read temperature....as the resistance changes (goes down) the voltage increases and the instrument reads higher.
You will need to install a dedicated temperature sensing device to operate a relay, as suggested, to turn your cooling fan on-off at the selected temperature. Most temp sensing devices have a dead band of 3-5 degrees between on and off temps, this may be adjustable, and is called the deferential setting.......but you need a separate sensing and switching device to control the fan. The best sensing position is in the coolant, as this is what you're trying to control. Sensing and controlling with the air temp thru the radiator will result in rapid cycling, on-off of the fan, without much change in coolant temp. Consider using the heater supply connection....you do not say what engine....I assume a B/RB....but it will depend on the physical requirements of the sensing element....the sensing element length or its sealing requirements.....it may be possible to use an existing coolant access point. Just my opinion of course.
BOB RENTON
 
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