Attic fan thermostat works but switch does not

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Old 05-30-18, 02:58 PM
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Attic fan thermostat works but switch does not

Hi.

I have an attic fan that has two inputs: one is thermostat and the other is a switch on the wall.

I noticed that the fan stopped working, so I assumed that the electric motor is broken (switch did not turn on the fan, did not check to see if thermostat can turn it on unfortunately). The old motor is emerson electric S55JXPJ-992 (photo).

I found replacement motor on amazon (https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1).

I installed the motor and realized that motor is turning in the opposite direct as I want it. The diagram on the motor showed how to reverse the direction (photo).

What the above diagram shows is that I need to change inner circuit red and black (there were 4 contacts, one for active electric wire from the source, one for neutral electric wire from the source, one red inner contact, and one black). I needed to switched the last two to change the direction of the motor.

Initially the motor was turned on by either the thermostat or the switch. But once I changed the black and red as I described above, the fan still turns on by the thermostat but does not by the switch.

Interesting thing is that, when fan is on by the thermostat, electricity flows through the switch. But when thermostat is off, no electricity through the switch.

Not sure what is going on...
 

Last edited by xerox2ooo; 05-30-18 at 03:19 PM. Reason: Realized error
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Old 05-30-18, 03:32 PM
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Just realized why schematically. I do not know why changing inner circuit of the motor did this. Perhaps while I was handling the motor, I created a short???

I attached the schematics:

Current circuit
Name:  attic 1.jpg
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Supposed correct circuit
Name:  attic 2.jpg
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Last edited by PJmax; 05-30-18 at 04:07 PM. Reason: added resized diagrams from links
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Old 05-30-18, 04:10 PM
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Welcome to the forums;

Your first diagram is completely wrong. You've drawn a direct short across the switch which means it cannot work.

Your second diagram is correct. Either the thermostat or the switch will turn the fan on. When one is on.... the other cannot turn it off. Your wall switch is called a bypass switch because you are bypassing the thermostat.

I also added L= line or hot and N = neutral.
 
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Old 05-30-18, 04:34 PM
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Hi. Thanks for changing the diagram.

Yes, the first diagram is not what I wish to accomplish. It just explains my current problem. As my post states, my fan was working correctly as the second diagram shows, but somehow, changing the electric motor (again, at first, it worked correctly, it was just spinning in wrong direction, ie I wanted CW, it was rotating CCW) and changing the inner circuit of the motor (as the manufacturer suggested, showing diagram on the motor which I posted) somehow changed the circuit from the second (correct one) to the first (which I understand is wrong, but it is how it is currently).

I am just trying to understand the situation. How it happened.
 
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Old 05-30-18, 04:45 PM
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Don't know. The bypass switch wiring should go directly to the thermostat junction box. It should not have anything to do with the motor wiring.
 
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Old 05-30-18, 05:08 PM
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That's why it is so odd...

It worked ok with the old motor. It worked ok with the new motor before I changed the circuit.

I did open the junction box but did not change or move any wires.

I used a voltmeter and checked across the switch. There is current only when thermostat is on. Somehow, short in the first diagram was created... So perplexed...
 
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