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  1. #1
    Join Date
    Apr 2013
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    Lennox Blower Motor Replacement

    Hi HVAC Experts!!

    I have a Lennox furnace and blower for the past 17 years or so... I replaced the blower motor myself about 10 years ago and then again a couple of days ago. So out of 17 years, I replaced the blower in there myself 2 times.. This most recent time, one of the barrings was going out, was making a slightly odd noise and had a different odor coming from it, circulating through the house.. ugh.

    My issue is with the current replacement I did a couple days ago.. I believe I installed everything like I should have but I'm having an issue. When I pulled the old motor out and installed the new motor, I noticed that the old motor shaft was easy to turn and would move freely. The new motor was more stiff to turn and stopped pretty quickly - might not be anything, but something to note.

    The current symptom I have is when the motor kicked in it started off with an odd sound, then sounded normal. This happened every time the blower motor kicked in, until today. It sounds like normal. Nice and quiet, blowing nicely and everything seems great.. until... a nasty burning smell is being pumped through the vents. I turned everything off, checked it out and the motor is running very hot. Obviously something is wrong.. Either the motor from the get-go, or I totally jacked up the wiring of it.

    So I'm asking for some help with my situation. Below is about as much information I though would be helpful to debug this issue.

    The motor image below shows the leads coming off the motor. There are two purple leads not shown going to the capacitor:
    Name:  usmotors-blower-motor-leads.jpg
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    This is the control panel showing where the leads from the motor are going:
    Name:  lennox-control-panel.jpg
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    Lennox schematic for the blower, etc. (left-side)
    Name:  lennox-panel-leftside.jpg
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    Lennox schematic for the blower, etc. (the rest, right-side)
    Name:  lennox-panel-rightside.jpg
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    This is an image of the motor sticker itself. 1/2 hp, 5 speed, etc...
    Name:  usmotors-blower-motor.jpg
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    This is the doc that came with the motor. It would be ideal to have different speeds, but just having it on HIGH is fine.
    Name:  usmotors-blower-motor-insert.jpg
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    Again, I greatly appreciate any advice and help with this. Otherwise, my current thought is the motor is hosed from the get-go, but if you can confirm the wiring would be greatly appreciated.

    Last edited by Hosed; 04-28-2013 at 04:56 PM. Reason: upload images

  2. #2
    Join Date
    Aug 2004
    North Richland Hills, Texas
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    This is not a DIY site.

    You didn't say what model of Lennox furnace you have, but I'm familiar with the motor you put in, and with the furnaces Lennox was making 17 years ago.
    I'm pretty sure the OEM motor was a higher amperage rated motor than the one you put in.
    There is more to selecting a motor than the HP and RPM listed on the data plate.

  3. #3
    Join Date
    Apr 2013
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    Thread Starter
    Thanks for the quick reply... It's a Lennox Elite Series (and I can't find a model number anywhere). I'm just trying to figure out if it's the motor or something I jacked up.

  4. #4
    Join Date
    Aug 2003
    Fort Worth, TX
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    I always check if the motor spins freely before I leave the parts house. If it doesn't, I ask for another motor on the spot.

    Mark is correct about amperage...if you don't match what was OEM, you can end up "hosed".
    Building Physics Rule #1: Hot flows to cold.

    Building Physics Rule #2:
    Higher air pressure moves toward lower air pressure

    Building Physics Rule #3:
    Higher moisture concentration moves toward lower moisture concentration.

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