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Old 01-21-2012, 01:23 PM   #1
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Help diag. blower motor issue in Lennox furnace


First, this is a great forum. I have read most of the post for the blower motor issue that I am having, but I can't find a solution.

I have a Lennox CB29M-51-2P and the blower motor seems to be dead but is it? After the heat pump has kick on for 30 or 40 seconds, I get both the red and green to light up on the WHITE-RODGERS thermostat. I walk out to the furnace and I hear a medium hum, but the fan is not running. I turned the power off to the furnace and take the door off to expose the blower and such. I turn the unit back on; hear the medium hum and the squirrel wheel is still not moving. I give it a little nudge and the fan starts to spin. BUT, it never runs at the higher speeds; it just keeps running at a low speed and does not move air throughout the house.

What do you think the problem is?

Scott

Model:
CD29M-51-2P
SN: 5804M02390
3/4 HP | 4.5FLA | 1 PH | 60 Hrz


Last edited by partsace; 01-21-2012 at 01:28 PM. Reason: fixed manu name on therostat...
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Old 01-21-2012, 01:28 PM   #2
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Help diag. blower motor issue in Lennox furnace


bad capacitor. or the motor bearings are seizing. should be able to easily spin it with your index finger ( the one beside the bird ).

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Old 01-21-2012, 01:36 PM   #3
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Help diag. blower motor issue in Lennox furnace


Yea, the motor spins just fine. In fact, I need to wait a minute for the motor to stop spinning before I can spin it again...

A: On the capacitor, does this give the motor the juice to spin?
B: Is the capacitor also in-charge of changing the fan speed or give the motor some more juice to spin it faster?

Scott
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Old 01-21-2012, 02:06 PM   #4
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Help diag. blower motor issue in Lennox furnace


Ok. Is it best to replace just the capacitor or both the motor and the capacitor?

Last edited by partsace; 01-21-2012 at 02:28 PM.
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Old 01-21-2012, 02:27 PM   #5
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Help diag. blower motor issue in Lennox furnace


Quote:
Originally Posted by partsace View Post
Also, is a transformer the same thing as a capacitor?
No.. it is not
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Old 01-21-2012, 02:29 PM   #6
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Help diag. blower motor issue in Lennox furnace


the capacitor gives it the extra juice to get up to speed and looks like this one and has a rating in mfds like 5mfd/370 VAC or higher. you can buy them at local electrical motor repair shops or Graingers or cozyparts.com for lennox stuff. under $20.
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Old 01-21-2012, 03:43 PM   #7
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Help diag. blower motor issue in Lennox furnace


Mine is 10mfd/370, so that's what I should be looking for, right? Or will a 7.5mfd/370 work?

Scott
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Old 01-21-2012, 03:45 PM   #8
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NO! Stick with the OEM rating.
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Old 01-21-2012, 03:49 PM   #9
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Help diag. blower motor issue in Lennox furnace


must be a 10 mfd.
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Old 01-21-2012, 03:51 PM   #10
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You guys ROCK!

I will give it a try.

Thanks,

Scott
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Old 01-22-2012, 03:55 AM   #11
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Help diag. blower motor issue in Lennox furnace


Good luck if you have to buy a new Lennox motor.
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Old 01-23-2012, 11:42 AM   #12
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Help diag. blower motor issue in Lennox furnace


We have heat! Thanks Yuri for your suggestions on where to get the part! Went to Grainger and got 2 of them for less than $20.00!

Scott
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Old 01-23-2012, 02:59 PM   #13
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Help diag. blower motor issue in Lennox furnace


yer welcome. thats why the damn things don't last, they are cheap. yrs ago an ac capacitor lasted 30 yrs but it was built like a tank, not anymore.

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