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Old 09-21-2008, 09:11 PM   #1
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Lennox G12 Blower Motor Problem


This afternoon there was a loud screeching sound as the blower motor totally froze up on my 16 year old Lennox furnace.

It's very obvious to me that the motor bit the dust, I have a few questions.

1. Do I need to remove the whole cage assy to remove the motor?
2. I see 3 bolts on the support side of the unit. If I remove those , is there eneough room to slide the motor out?
3. Where is a good place to get a replacement motor?

I'm pretty good at fixing my appliances (thanks to the internet) but have not touched the furnace. Looking for some advice here.

BTW - I'm in SoCal and luckily the weather is cooling down. some

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Old 09-21-2008, 10:16 PM   #2
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You should be able to loosen the set screws on the squirrel cage and then unbolt the motor and slide it out. If you have to tap it out oil the shaft and use a brass drilf so you don't mushroom the shaft.Make sure you cut the power off.
WW Grainger would be a good source or A/C supply if they will sell to you. A good motor repair may be able to fix it also.
Good luck

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Old 09-21-2008, 10:53 PM   #3
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Once you get the motor out, and if you're certain that the electrical part of it is OK, and just the shaft froze up, you can usually replace the bearings yourself.

If it's held together with bolts (usually 4), first mark where the endbells go on the rest of the frame. That way, you'll put it back together the same way. Usually, you have to pry the endbells off, and when you get the rotor out, if they're ball bearings, they'll be pressed onto the shaft. It usually isn't any too difficult to remove them, they're not all that tight.

Once you get the bearings off, look for a number, 6203ZZ is pretty common for this type. Grainger has them, as do many other industrial supply houses. They're about $8 or so, a lot less than a new motor. Even if only one is bad, replace both.

This is most likely a PSC (permanent split capacitor) motor, and if so, when you're done, you'll have basically a new motor. Bearings are the only thing that wears out on this type of motor.

Rob
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Old 06-28-2012, 03:35 PM   #4
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Lennox G12 Blower Motor Problem


Could you please tell me which G12 Blower Motor has bearings?

I just took apart my Lennox G12 after the blower motor failed with the buzz of death. Come to find out there was so much dust and gunk in the motor and squirrel cage that it simply refused to turn, even with the umph of the start capacitor. I used an air compressor and WD40 wipes to clean what looked like decades of neglect (I inherited this house and all its terribly neglected appliances, so don't be h8n) out of the squirrel cage, the blower itself and the PSC blower motor. This thing doesn't have bearings at all, it has bushings! No bearing kits to buy, didn't even have to replace the blower motor, just gave it a good cleaning and put it all back together. Saved me plenty on this 107 degree day in St Louie! Timing was so 'perfect,' it's the hottest day on record! The service call alone would have been enough to make me pass out, much less the heat.
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Old 06-28-2012, 08:25 PM   #5
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Wow,

This was an old thread. I was surprised when I looked at the date and saw that my fix was almost 3 years ago.

I also see that i failed to thank everyone and give an update...... If memory serves right it took me a couple of hours and about $20 for the parts. I count this as one on my successful repairs.

Thanks for all that posted to help me on this.
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Old 06-28-2012, 08:44 PM   #6
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Lennix G12 Blower Motor Problem


So you're not going to elaborate? Did you swap out the run capacitor or did you have to venture through removing the actual motor?
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Old 06-28-2012, 09:25 PM   #7
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One of the bearings had given up. I went to Grainger, got the bearings that were suggest and put them in.

Easy as pie.
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Old 06-28-2012, 09:55 PM   #8
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Quote:
This thing doesn't have bearings at all, it has bushings!
What you are calling bushings. Are actually sleeve bearings.
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Old 03-12-2016, 06:03 AM   #9
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Re: Lennox G12 Blower Motor Problem


Hi there. Looking at this old post and have a similar issue with my older G12 blower motor. The info posted was extremely helpful, but I'm curious if you can share the process to actually get to the motor itself? I was curious about those 3 screws on the right side, but not sure they're actually involved in the removal? I'm guessing that the only way to the motor and squirrel cage is through the front, but would appreciate any tips you can share. Thanks!!
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Old 03-12-2016, 06:43 PM   #10
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Re: Lennox G12 Blower Motor Problem


You have to pull the blower assembly out. If you're lucky it will be two bolts at the front, assembly slides out on rails.

In some old furnaces it may not be on rails.

Check capacitor and for power before pulling the assembly. See if the wheel spins freely.
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Old 03-13-2016, 01:18 PM   #11
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Re: Lennox G12 Blower Motor Problem


Thanks SO much for the advice. Was able to take it out today (with a bit of a struggle and a few cuts on the arm), cleaned and oiled it and purring like a kitten again! Thanks for being so helpful - I really appreciate it!!
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Old 03-18-2016, 06:31 AM   #12
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Re: Lennox G12 Blower Motor Problem


Just a quick follow up on this. As is said before, your advice was great and my blower motor is purring now. However, for some crazy reason it now turns back on again for about 5-10 seconds after it shuts off when the temp has risen to what the thermostat is calling for. Anyone had this same issue and know how to fix it - or even if it needs to be addressed?

Thanks!
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Old 03-18-2016, 01:40 PM   #13
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Re: Lennox G12 Blower Motor Problem


I'd be checking to see if the manual fan control "off" temp needs to be adjusted to run a little lower (longer) or if the "on" fan control temp setting needs to be raised a bit higher.

How long does it take the blower to come on after initially firing the furnace and is the temp coming out of your heating ducts at the end of a heating cycle ..... warm, neutral or cool?
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Old 03-18-2016, 03:26 PM   #14
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Re: Lennox G12 Blower Motor Problem


Check the fan/limit switch settings - adjust as needed.

If you have the dial type:

1. Remove the metal cover on the fan/limit switch

2. Check the position of the pointers. Adjust as needed but hold the dial as you do so.

Lowest is fan off temp -> Set to 90 - if fan continues to cycle back on, go lower.

Middle is fan on temp -> Most of the older standing pilot G8-12 furnaces run hot. The ON setting may be at 140f+ from the factory - I suggest dropping it down to 110-120f to save gas.

The sooner the fan comes on, the less gas gets wasted. With these old furnaces the burner can be on for several minutes as the furnace warms up before any heat gets delivered. This is particularly inefficient in mild weather, especially when the heating cycles are very short.

Highest is the high limit setting - don't touch that.
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Old 03-18-2016, 10:30 PM   #15
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Re: Lennox G12 Blower Motor Problem


Quote:
Most of the older standing pilot G8-12 furnaces run hot.
This is a generalization; the rating plate will tell you what the temp rise range is.

Most natural draft style furnaces do run with a 70+ temperature rise.

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