Can someone explain this fan switch for me? - Page 2 -

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post #16 of 18 Old 04-18-2013, 09:41 AM
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1986 CJ7 
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Originally Posted by CJ7KAHUNA View Post
The way I understand it is that the motor has a single lead for power going in. If the power feeding that lead is reduced the speed is reduced proportionately. If the power is a full 12v the fans run at full speed. Unless I am missing the boat the fan motors do not have dedicated windings or portions that are dedicated to certain speeds.

What I am not sure of is if you have 12v going through the resistor circuit reducing the voltage and it meets a full 12v provided by the high speed relay on the other side of the resistor how or if that would affect the full 12v load for high speed. I am pretty sure that beings its coming from a single 12v source you wont increase or multiply voltage.

All of tht being said - what i would like to do is simply feed a 40 amp relay for the low speed circuit off of T1 and have T2 feed a 70 amp relay to bring in high speed as demand requires. Ideally T1 and T2 will not be energized at the same time. But even if they are I am not sure how much of an issue that will be to the motors.
Yup. This is how the contour fans are designed. If you look at the factory wiring diagram for the contour fans, you'll see that they are wired exactly as you describe.

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post #17 of 18 Old 05-02-2013, 02:06 PM Thread Starter
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Here is my idea for an elementary 2 speed fan control module.

Concept is simple and would utilize the factory Contour wiring - I have a relay base that will accept 2 relays that I picked up at the U-pullit for $3. I will take an exterior gang box and make and opening in the top edge for the actual relays to access the base, mount the relay base, circuit breakers and terminal block inside the box. Mount the box close to the fan, wire it up and put the cover on. The actual relays are exposed at the top of the box but everything else is weather proof. I dont think the relays being exposed will matter much but if so it wont be too difficult to fabricate a cover for them.

I know the drawing is cheezy but does anyone see a reason it wouldn't work?
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post #18 of 18 Old 05-02-2013, 07:16 PM Thread Starter
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Anybody? Was hoping to get a little feedback from those of you that have some electrical background.

That being said - wheres the Hammer?
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