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Discussion Starter · #1 ·
Hey guys--

I am getting ready to install the temperature relay thingy that makes the electric fan turn on and off at certain temperatures, and I wanted some opinions on the best place to get the +12v source. I don't really want to connect straight to the battery, as that will cause the fan to run even when the car is turned off if the coolant temperature is hot enough. I thought about the right side of the solenoid as the source, but wouldn't that cause the fan to pull its juice from the battery instead of the alternator when the car was running? If that is the case, then would the best solution be to use the alternator as the source?

One more question while I'm at it, is it really necessary to have a manually operated switch for the fan in the interior of the car? I don't really want to mount another switch inside my car if I don't have to, so hopefully someone who is using and electric fan can comment on the reliability of these temperature relay units.

Thanks for any help.

Dave

Thanks
Dave
 

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I would go directly to the +solenoid. Makes no difference where you get the power, so long as you don't overload a circuit. A 20 amp circuit breaker in the system would be a wise move.
Personally, I wouldn't have a problem with the fan staying on until the engine was cool...
 
G

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I highly recommend getting the power directly from the battery side of the starter solenoid, with a 20amp fuse or circuit breaker in between.

If by the "right" side of the starter solenoid you mean the side that connects to the starter, no, this will not help you. The starter side of the solenoid only gets juice when you're starting the car.

Most electric fan relay systems will have a line that can be connected to ignition hot, which will make it so the fan is only on when the car is on. It doesn't draw the fan power from this source, though, only the power for the relay itself.

Also, use some reasonably heavy gauge wiring (like at least 14 gauge) to run the fan. Depending on the fan, they can pull some reasonably large amps.
 

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The relay kit should have come with directions, which should have instructed you to use the battery-side of the solenoid for a power source. Then the trigger of the relay would go to a switched source so that the fan only runs when the key is in the run position.

Letting the fan run until the engine is cool is not a terrible thing either. It won't kill the battery or anything like that.

My fan is connected directly to the batt-side of the solenoid. There is a relay in the ckt as well, so it only runs when the key is on.
 
G

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I was wondering why you think the fan will run continuously if connected to the battery directly? You are not connecting the fan to the battery - but you are connecting the temp switch right?? The temp switch will only come on and off at pre set temps...so it needs to be constantly powered to know when it reaches those temps.

Say you turn your car off after a long drive...the engine and fluid temp is still hot right? Well that is why the use the temp switch and a constant 12 volt source. The fan will continue to run until the temp lowers - then the termostatic switch will shut off....that is if the temp switch is mounted in the radiator, or block etc.

Ever walked by a new car (honda, acura, etc) and heard a fan running but no one in the car???

There ya go...

Fastlane Ford
 
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