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partsace 01-21-2012 01:23 PM

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?


SN: 5804M02390
3/4 HP | 4.5FLA | 1 PH | 60 Hrz

yuri 01-21-2012 01:28 PM

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

partsace 01-21-2012 01:36 PM

Motor free
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?


partsace 01-21-2012 02:06 PM

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

HvacWiz 01-21-2012 02:27 PM


Originally Posted by partsace (Post 830156)
Also, is a transformer the same thing as a capacitor?

No.. it is not

yuri 01-21-2012 02:29 PM

1 Attachment(s)
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 for lennox stuff. under $20.

partsace 01-21-2012 03:43 PM

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


hvac5646 01-21-2012 03:45 PM

NO! Stick with the OEM rating.

yuri 01-21-2012 03:49 PM

must be a 10 mfd.

partsace 01-21-2012 03:51 PM

You guys ROCK!

I will give it a try.



bobelectric 01-22-2012 03:55 AM

Good luck if you have to buy a new Lennox motor.

partsace 01-23-2012 11:42 AM

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!


yuri 01-23-2012 02:59 PM

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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