Furnace Blower Motor Wiring Help

[RickDaTuner]

So my Furnace blower motors bearing decided they were going to pack it in, and now every time the blower motor tries to start, it just hums very loudly.

Out of necessity, and not wanting to pay a plumber to come an diagnose a seized blower fan, I went ahead a bought the only blower motor I could find from a home hardware

My issue is that the old blower motor is a 3 speed unit, which was wired into run as a single speed, and has a start/run capacitor, and uses 5 wires to run,
-
neutral/white
-power/blue
-cap 1/brown
-cap 2/ brown white
-ground/ green yellow

The new new motor, came with no wiring, just a board with 4 connections

- red #2
- black #5
- Jumper #1
- jumper #4

My question is...

Can i run the new motor with out a capacitor, and if not then how do I wire one in, if I can, or did I just purchase the wrong motor?

From the info I have been reading online it seems that I would need to wire in a capacitor to the Red #2, and power/live wire from the power source? is that right or am I looking to start a fire? lol

Thanks for the help, I would apreciate not having to wait till mid next week for a new blower motor, or a $600+ repair bill to call a plumber.

Old Motor Wiring Plaque

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New Motor Wiring Plaque

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New Motor Connectors

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[Crazyjoker77]

new motor doesn't need a cap its a different type of motor.

your hot wire(ungrounded conductor) goes to #1
Neutral(grounded conductor) goes to #4


you can leave the jumpers alone. If it spins the wrong way swap these two(red+black wires of the motor).

And of course the green screw is for the ground wire.

Biggest issue is that the speeds are significantly different 1075-1700. It may be very loud now... It will work but not really recommended.

[rx7_turbo2]

Furnace fan motor speeds are matched to a number of characteristics of the furnace. Tough to say how well this will work, only one way to find out I guess.

[RickDaTuner]

Originally posted by Crazyjoker77
new motor doesn't need a cap its a different type of motor.

your hot wire(ungrounded conductor) goes to #1
Neutral(grounded conductor) goes to #4


you can leave the jumpers alone. If it spins the wrong way swap these two(red+black wires of the motor).

And of course the green screw is for the ground wire.

Biggest issue is that the speeds are significantly different 1075-1700. It may be very loud now... It will work but not really recommended.

Thanks for the help.

This house has a long history of furnace motor failures, and shady plumbers. the original furnace had a 1500rpm blower motor installed, which was then replaced for another unit, and then once again replaced for this unit.

I suspect that this unit failed prematurely for not pushing enough air, and causing long run times, in order to heat the house.

Hope this one last much long than the last two, they averaged about two years each.

[Crazyjoker77]

its almost always better to go with a too fast of a motor than too slow. If the original was a 1500RPM you should have good luck with the 1700.

You did say the bearing seized which generally isnt caused by heat issues but lack of lubrication/cleaning. Your new motor has sealed bearings your old one doesn't seem to be from your pic. The lack of maintenance probably killed it.

A bad capacitor will also cause the motor to HUM and not spin. Does the shaft spin freely by hand? you may only need a 10$ cap.

[RickDaTuner]

The motor is stiff to spin by hand. replacing the cap was the first thing I tried, and it was all the same.

The last plumber who installed the last unit has been in bi-annually to inspect the furnace and the water tank, as part of a service he offered after he replaced our hot water tank and replaced this blower mot under warranty, hence my comment of a shady plumber.

Thanks again.

[Maxt]

Originally posted by rx7_turbo2
Furnace fan motor speeds are matched to a number of characteristics of the furnace. Tough to say how well this will work, only one way to find out I guess.

Bingo... Also some blower wheels are not rated for higher rpms,also when increasing RPM, required power changes by the cube of the proportion, so you may over amp the faster motor.
Thats ISIR motor is not the right replacement for a multispeed PSC motor.

[dirtsniffer]

Anyone else click on this thread hoping the OP was Mar?

[RickDaTuner]

Well the new unit is in and working for now, I will have to order up a proper unit tomorrow, but its nice to have heat in the house again.