Blower motor question

[mstride]

I have a 15+ year old Keeprite Furnace that wouldn't start up. On investigating, the limit switch is tripping due to the blower motor not powering up.
It seems to be getting power, just measured with an AC pen.
Pulled the blower motor, Emerson model M55BMCNR-216. It's a 4 wire motor, with Green, Blue, Yellow and Red wires.
Resistance from green to each of the other wires is O/L, so open.
Resistance between Blue, Yellow and Red are all below 10 Ohms.

I'm assuming that the motor's fried due to the O/L between Green and each of the other wires, but wanted to see if anyone had any experience with these motors before I spend the money on a new one.
Thanks

 

[Breplum]

We always check the start capacitor first. You need a meter that has capacitance capability.

 

[Sponsor]

 

[Fitter30]

230 vac three phase motor? Need a volt meter to make sure u have all the phases. Green is ground. The other three wires resistance should be a close if not the same.

 

[matthewatmtsidottech]

I have a 15+ year old Keeprite Furnace that wouldn't start up. On investigating, the limit switch is tripping due to the blower motor not powering up.
It seems to be getting power, just measured with an AC pen.
Pulled the blower motor, Emerson model M55BMCNR-216. It's a 4 wire motor, with Green, Blue, Yellow and Red wires.
Resistance from green to each of the other wires is O/L, so open.
Resistance between Blue, Yellow and Red are all below 10 Ohms.

I'm assuming that the motor's fried due to the O/L between Green and each of the other wires, but wanted to see if anyone had any experience with these motors before I spend the money on a new one.
Thanks

I am in the same boat, as mine stopped last week actually. Possible time bomb in the software? I have this model furnace and the blower fan motor starts up for 2 seconds and then stops and repeats until the flame goes out. C9MPV07512B1 (2005) .

It is a DC motor so there is no capacitor. The housing of the blower controller needs to be removed from the entire drum of the blower to get to the guts, but a similar picture online shows all pcb/components are hidden under some grey epoxy.

Is the Green the common on this motor? I assume so, because it is thinner than the rest.

I do not see a transformer for the AC to DC, do you know where it is? I am thinking it is buried in the grey epoxy. Are you getting 24VDC off the leads when the blower is called on? I only see the 120VAC to 24VAC transformer, so I am very confused about where it is getting 24VDC from as the diagram does not include any info on the blower controller.

I really don't want to replace this unit, so a bush fix would be ideal...

 

[Fitter30]

C9MPV07512B1. Is this a motor number or furnace and what brand? Take a pic of the wiring diagram. The motor is a ecm need brand and.compleat model . Back of the motor has the electronics in it

 

[Breplum]

For ECM motors, a ECM test setup is required. No more is a voltmeter an option.
From SupplyHouse in reference to the $500 diagnostic tool: "GE, who makes a large share of these motors, reports that 41% of the motors returned to their factory actually have "no problem found". That means someone made an expensive misdiagnosis; it also means the real problem has not been corrected by replacing the motor. Almost any mistake in diagnosis on an ECM system will cost the Tech (or his customer) much more than this tool does!"