Hi,
I have a York furnace (model P4USD16N10510A - natural gas) that stopped working this morning. Initially, I would hear the furnace fire, but the blower wouldn't spin. It had a loud hum to it, like it was stuck. I opened up the unit, and was able to spin the fins by had. This is while the thermostat setting was on auto. I then went to check it again, and set the thermostat to fan, just to see if the blower would work. Still same issue, loud hum coming from the unit. While it was humming, I stuck my hand in the blower (I know, not the smartest thing, but a cold (temperature) wife makes you do things like that) spun the fins, and it still didn't do anything. I shut off the unit with the emergency switch, scratched my head for awhile, and figured let's give it another shot. I flipped the emergency switch back on (thermostat still on fan) but now the unit did nothing. I pressed the reset(?) button that was in front of the blower, and the gas kicked in and ignited, but the blower still didn't spin. And now, holding in this button is the only way for me to get the furnace to work. So, before I get myself into anymore trouble with my Queen, can someone please give me some pointers on how to diagnose and fix this?

It is possible the blower motor is defective. If you decide to replace the motor also but a new capacitor that is sized for the new motor. The reset you pushed is a high limit and it is safety device so stop pushing it and test the motor circuit and replace the motor if defective.

Ok, now I've replaced the motor and capacitor, but now I have some questions on wiring in the new motor (A.O. Smith F48N78A01 - 4 spd). It has 7 wires while the old motor had 5 (3 spd). The way the old motor (Emerson k55hxjfm-2835, pt no 024-23218c) was hooked up:

Brown wire - capacitor
White wire - capacitor (another wire was run from this side of the capacitor to the white power wire on the furnace)
Black wire - relay
Blue wire - spade connection
Red wire - taped up

Now according to the wiring diagram on the new motor, the wires are for:

Brown wire - capacitor
Brown/white stripe - capacitor
White wire - power
Black wire - Hi spd
Blue wire - MH spd
Yellow wire - ML spd
Red wire - Lo spd

So, if think this is what I'm supposed to do:
I hook the brown wires to the capacitor, tape the red wire, tape the white wire, tape the yellow wire, plug the black into the relay, plug the blue into the spade connection, and run the white house power to one side of the capacitor.

I haven't hooked anything up yet, so any help on how to connect this would be appreciated.

Ok, now I've replaced the motor and capacitor, but now I have some questions on wiring in the new motor (A.O. Smith F48N78A01 - 4 spd). It has 7 wires while the old motor had 5 (3 spd). The way the old motor (Emerson k55hxjfm-2835, pt no 024-23218c) was hooked up:

Brown wire - capacitor
White wire - capacitor (another wire was run from this side of the capacitor to the white power wire on the furnace)
Black wire - relay
Blue wire - spade connection
Red wire - taped up

Now according to the wiring diagram on the new motor, the wires are for:

Brown wire - capacitor
Brown/white stripe - capacitor
White wire - power
Black wire - Hi spd
Blue wire - MH spd
Yellow wire - ML spd
Red wire - Lo spd

So, if think this is what I'm supposed to do:
I hook the brown wires to the capacitor, tape the red wire, tape the white wire, tape the yellow wire, plug the black into the relay, plug the blue into the spade connection, and run the white house power to one side of the capacitor.

I haven't hooked anything up yet, so any help on how to connect this would be appreciated.


On a furnace the motor wired for 120 volts the white wire is common. The other colors except brown and brown with white stripe are power for the speeds. There is a label on the side of the furnace for you to use in wiring.

I am also providing a generic wiring diagram. LOOK at PSC motor in the lower right side.

HVAC1000,
Thanks for the reply. There wasn't any wiring diagram on the furnace, just dirt - but I'll wipe it down and look again. From what I gather, I should:
Plug the brown wires to the capacitor
Hook the white wires together
Plug the black wire to the relay
Plug the blue into the spade connector?

I guess my main question is which one goes to the relay, and which one goes to the spade connector, and why?

So on the old motor, the black and blue wires were for the hi and med spds?

As I said there is a wiring diagram on every NEW motor. That is the diagram to use since it is specific to that new motor. The other diagram was provided as a example. The wiring specific to the relay in the unit is listed on the furnace wiring diagram. If that is not available it will cause you to find a copy of the origunal diagram since all else will be guess work. The tab or pin or spade connections represent usually 2 different voltages one being 24 volts for speed control/relay activation and the others for 120 volt speed selection process. Be dang sure before any wiring hookup since the wrong wires (120 volt) to the low volt side (24 volt) of the relay can cause a disaster with the system wiring and other controls..

Note I would also check the model number you posted for that furnace. I cannot locate it in my data base so I cannot be of help with a wiring diagram. Besides posting the correct model you might also post all the numbers on the relay being used. That may be of a small help.

Ok,
I found the wiring diagram for the furnace, which is in the file attachment. It looks like my last thought process is correct. Just take a quick look at the diagram and let me know.
Thanks again.

Wire the new motor Exactly like it says for the new motor.

Tape off all speed connections you will not use. I do not recommend running the white wire to the capacitor but to the neutral leg in the furnace where it belongs according to the wiring for the new motor. I always recommend wiring as the new motor requires since while it may work wired the old way there is no real way to find out without taking a chance of frying the new motor.

Ok, now I've replaced the motor and capacitor, but now I have some questions on wiring in the new motor (A.O. Smith F48N78A01 - 4 spd). It has 7 wires while the old motor had 5 (3 spd). The way the old motor (Emerson k55hxjfm-2835, pt no 024-23218c) was hooked up:

Brown wire - capacitor
White wire - capacitor (another wire was run from this side of the capacitor to the white power wire on the furnace)
Black wire - relay
Blue wire - spade connection
Red wire - taped up

Now according to the wiring diagram on the new motor, the wires are for:

Brown wire - capacitor
Brown/white stripe - capacitor
White wire - power
Black wire - Hi spd
Blue wire - MH spd
Yellow wire - ML spd
Red wire - Lo spd

So, if think this is what I'm supposed to do:
I hook the brown wires to the capacitor, tape the red wire, tape the white wire, tape the yellow wire, plug the black into the relay, plug the blue into the spade connection, and run the white house power to one side of the capacitor.

I haven't hooked anything up yet, so any help on how to connect this would be appreciated.


Hello sir. Ive got the same model emerson motor... Two questions sir. I'm going to be doing the same thing. I tried to replace the capacitor on the old motor and no luck it still makes a loud howling sound before finally reaching full speed.

What capacitor did you buy, is it possible to get a part number from you?
And 2. The old emerson motor is rated at 370 volts and now the new one is rated at 120 volts how is this wired.

Any input would be great Thanks

What capacitor did you buy, is it possible to get a part number from you? and 2. The old emerson motor is rated at 370 volts and now the new one is rated at 120 volts how is this wired.

The capacitor needed for your motor should be listed either on the motor's nameplate or on the box it came in. It will will say, for example, 7.5 microfarads @ 370VAC. The 370 VAC you see is the capacitor NOT the motor.

The capacitor needed for your motor should be listed either on the motor's nameplate or on the box it came in. It will will say, for example, 7.5 microfarads @ 370VAC. The 370 VAC you see is the capacitor NOT the motor.3:52 A.M. We're you up that early... or that late?

Both!