Furnace blower motor replacement wiring help!

Old 12-05-11, 09:11 AM
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Furnace blower motor replacement wiring help!

Hi pros,

I found this thread very helpful but have a few more questions to ask, if somebody could help, I would highly appreciate it.


I have 3 questions about the wiring of a 6 wire new replace blower motor I just bought to a 4 wire old one.

The new motor is this one, I believe: 3583 1/4 hp 1075 115 v 3 Speed Furnace Blower Fan Motor | eBay (I bought mine from a local supply store)

1) Where should I install the capacitor? Should I connect one leg of the capacitor to the brown wire of the motor and another leg of the capacitor to the brown with white wire of the motor? (the old shaded-pole motor doesn't need a capacitor, the new PSC-type motor does, but I don't know where to use the capacitor)

2) Regarding the feed wire low speed connection for heating (the red feed wire), Which wire should I connect to? is it to the "Med High" motor wire (yellow in color), or the "Med Low" motor wire (orange in color).

3) Regarding the cw/ccw rotation, which connector should I connect to? Should I connect a purple wire on the motor to another purple wire on the motor or yellow wire on the motor for the rotation? Anybody know which color should I connect to make the right rotation?

4) The old motor had a max amp of 9.5, the new motor has a much lower max amperage (mine is 3.9), will that cause any issue?

Thank you very much for any help. I am waiting for any help online here!
Old 12-17-11, 03:04 PM
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Connect the brown wire with a white strip to one side of the capacitor. Connect the brown wire to the other side of the capacitor.

Medium high is a safe place to start. Check the rise in temperature across the furnace when it is heating.

The curve of the blower wheel blade scoops air and blows it into the ducting. Try the factory setting for 2 seconds, remove power and look at the blower wheel as it slows down. If it is spinning backwards, reverse the rotation.

Permanent split capacitor motors are much more efficient than shaded pole motors. This is still a huge difference. Was the old motor 1/4HP?

Many shaded pole motors are resilient mount (bracket grabs the ends). Did you match the frame number? Is this motor already installed and ready to be wired?

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