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    James48843's Avatar
    James48843 Posts: 3, Reputation: 1
    New Member

    Feb 10, 2008, 07:58 PM
    Furnace Squirrel cage suddenly loud
    This is a ten-year old Goodman GMPN100-4.

    Today the motor suddenly increased in noise. I went downstairs to look it over, and the sound level is very loud, coming from the motor/squirell cage area. I took off the door, reached in, wiggled the squirrel cage to see if it was loose, and it did not appear to be. When rotated by hand, slowly, I could not feel any abnormal resistance, and it turned freely, and appearently, quietly.

    When I pushed the contact to watch it start, however, the cage began to rotate very loudly, and seemed to be out of balance. This runs off a 1/2 HP motor, with three mounts around the shaft, I believe.

    So my question is: Is the motor bad, or is the squirrel cage bad?

    I plan to call for professional service in the morning. I have found motors on-line varying from $125 to $289 for the motor (P/N B13400-20), and around $80 for the cage blower wheel (P/N B13680-47). I figure the service guy is probably going to charge me considerbly more, but if it an easy fix, I might try it myself first. However, I'm not sure to try replacing the motor first, or go for the wheel first.

    What do you think? Do motor bearings go out, or is there something I have missed?

    Thanks in advance for any opionons out there. It seems to be running OK, although it's running with a vibration now, and I hope it will hold out till morning.
    hvac1000's Avatar
    hvac1000 Posts: 14,540, Reputation: 435
    Heating & Air Conditioning Expert

    Feb 10, 2008, 08:02 PM

    Motor mounts
    Cage to motor attachment bolt
    Lubrication of motor if possible.
    Power feed to make sure only one speed of the motor is getting power at a time.

    Actually I believe your motor is toast but you can try the above.
    James48843's Avatar
    James48843 Posts: 3, Reputation: 1
    New Member

    Feb 10, 2008, 08:11 PM

    I don't know if I can reach the motor mounts or the cage to motor attachment bolt to check, without disassembling the blower assembly and pulling it out. If I do it now, I risk not being able to put it back together before morning, which means we'll be in for a very, very cold night- it's minus 3 outside now and falling.

    Capacitor is fine, it's not that. Power feed - I highly doubt, as nothing has changed in that regard- but I do believe you may be right on the cage to motor attachment bolt- some of the other bolts seems to be loose, so that one is a real possibility. I don't know if I can lube the motor- neither the owners manual nor the parts manual show anywhere to lube- but I very well may pull it out and take a look.

    And I think you are right- the motor is probably toast.

    But you gave me a good clue to look for the cage to motor attach bolt. I may go investgate first thing in the morning before ringining up the service man.

    Thank you very, very much for the quick answer.
    T-Top's Avatar
    T-Top Posts: 1,871, Reputation: 100
    Ultra Member

    Feb 10, 2008, 08:19 PM
    Sounds like the hub has separated from the blower wheel, common problem. A new blower wheel should take care of the problem.
    letmetellu's Avatar
    letmetellu Posts: 3,151, Reputation: 317
    Ultra Member

    Feb 10, 2008, 09:08 PM
    T-Top gave you the best advise. We have had quite a bit of trouble of the blower wheels tearing up, either the hub coming lose or the crimp joints of the fins becoming lose and the wheel going out of balance. A new wheel some where around $60, no telling about the labor. It is something you can do yourself if you have those type skills.
    James48843's Avatar
    James48843 Posts: 3, Reputation: 1
    New Member

    Feb 11, 2008, 07:50 AM
    Thanks for the answers-

    The furnace quit at 5 a.m.- after having been very loud from about 8 p.m. until it quit.

    I tore it apart to dissect the mode of failure, and it was a bad squirrel cage blower. It basically self-destructed. Looks like the above answers were correct- it looks like the crimps shifted, put it out of balance, and then it was a very short matter of time before catestrophic failure.

    I called the service guy at 6 a.m. He just left. The motor was still working, although there was just enough play in the shaft to convince me to replace the motor at the same time.


    $389 for a motor
    $179 for a blower cage fan.
    $89 labor.

    The look on the guy's face when he walked in, and I told him it was a failed squirrel cage blower, as described on "Ask Me"...


    Thanks all.

    I now have heat.
    wmproop's Avatar
    wmproop Posts: 3,749, Reputation: 91
    Ultra Member

    Feb 11, 2008, 05:07 PM
    Can you get your hands inside the squirrel cage,, chech for UFO,, something may have found its way inside the cage like a piece of paper, a piece of the filter, or even a mouse, and has made it be out of balance,, have seen it happen,
    letmetellu's Avatar
    letmetellu Posts: 3,151, Reputation: 317
    Ultra Member

    Feb 11, 2008, 07:59 PM
    Very high prices, except for the labor.
    bkvanbek's Avatar
    bkvanbek Posts: 1, Reputation: 1
    New Member

    Nov 19, 2008, 06:24 AM
    I have a similar problem with the same blower. Did your blower wheel break? I think it is my motor was squealing and has now quit.
    dpmartin's Avatar
    dpmartin Posts: 1, Reputation: 1
    New Member

    Aug 16, 2010, 09:16 AM
    In my case, the squirrel cage was simply out of balance. Add weights to rebalance if this is your problem.
    rhgeorge's Avatar
    rhgeorge Posts: 1, Reputation: 1
    New Member

    Sep 12, 2010, 04:06 PM
    I had the same problem as James48843. His excellent write-up describes what happened to me. Just like James, I heard a slight noise coming from the blower. I reached in (after disabling it of course:)) to see if I could detect if the wheel was loose. It didn't appear to be, and since we were going to replace the whole system in a month or two, I wasn't too worried. Early the next morning, at about 2:30AM all hell broke loose and the blower wheel destroyed itself. Luckily, a cool front was on its way to St. Louis in a day or two, so we were able to survive. Based on what I've read on this website, it would appear Goodman has a design problem with their blower wheel.
    Lesson1's Avatar
    Lesson1 Posts: 1, Reputation: 1
    New Member

    Sep 24, 2010, 06:10 AM
    Suddenly yesterday we heard a loud noise that sounded like a helicopter hovering over our house. After searching outside and in the house, we found the noise coming from our basement. My husband found the noise coming from the furnace.
    My husband turned off the furnace. He checked the inside of the furnace and low and behold! HE FOUND A DEAD SQUIRREL IN THE SQUIRREL BOX. H removed the animal and now the furnace is working fine.
    So maybe you could check for something caught in yours.
    jfieldson's Avatar
    jfieldson Posts: 2, Reputation: 1
    New Member

    Jul 27, 2013, 12:20 PM
    I don't have the answer, but I'm replacing a blower wheel number B1368047. The only one I can find is B1368047A on which the set screw is on the convex face of the center plate. On the B1368047, the set screw is on the concave face of the plate. The B1368047A will not go as far onto the motor shaft, so the wheel and motor vibrate causing a loud noise throughout the house. The vibration will also damage the motor. I've ordered the correct number, B1368047 from others, but continue to received the B1368047A. My furnace is Model GMNT100-4B, so it's not 10 years old, and has only been installed for 8 years. The serial number is 0405706501. Does anyone know where I can find the right part?

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