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BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 22002
Experience:  Endorsed for unlimited heating, cooling, oil burners, boilers, refrigeration, hydronics
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I have a Lennox furnace mdl# G12Q3-137 ser# G12Q3-137-2 (the

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I have a Lennox furnace mdl# XXXXX ser# XXXXX (the Q could be a 0). I have replaced the capacitor, oiled the motor thru the ports with no luck. The blower fan does not always start turning like is is supposed to. When the furnace comes on everything is as it should be except when the capacitor juices the motor to start the fan turning-it just buzzes, the motor that is. I can give the fan a little nudge and it will start working and the buzz stops. Motor doesnt over heat @ the end of the heating cycle (not hot to the touch). There is nothing in the blower housing to hinder the fan. Bearings need to be replaced on the blower fan? When the furnace is running, there is a rythmic noise while the fan is turning.



It sounds as if the start windings are weak. Are you sure the new capacitor is good?

Customer: replied 6 years ago.
I bought it the other day new from a vendor here in town, so I "assume" it is ok.

Well. you have done the right things.

The confusing issue is if the motor starts with a push it is normally capacitor related.

If stiff and resistant then it is motor.


If the capacitor is indeed good, and you are getting 120v, then the start windings are too weak and the motor must be replaced.

Customer: replied 6 years ago.
If the start windings are going bad, wouldnt that cause the motor casing to become warmer than normal/hot to the touch? Would this also cause the rythmic noise while the furnace is running?

It depends on the failure internally...


here are your choices -

bad bearings.....but those would not allow it to be push started and run easy and once running the motor would get extremely hot. Plus would be a metal noise.


Bad capacitor....same symptoms as you now have, except you already replaced it.


Bad windings....depends on if the condition of the wings as to what heat and rotation is attempted.


less than 120v would result in heat and motor soinning at reduced rate.


The rythem noise could be housing , squirrel cage etc, and the motor would be bench tested for that.


you can remove the motor and take it to any motor repair shop and they test it for free.

Customer: replied 6 years ago.
to pull the blower housing all I should have to do then is to rmove the two nuts located at the front of the furnace and the housing should drop down and I will be able to remove the entire housing from the furnace, after disconecting the wires and pull the motor from within the housing - or is there something else that I should know about?
Nope that should be it. Sounds like you grown pretty familiar with her
Customer: replied 6 years ago.

I sure appreciate your help in this matter. I know someone that might benefit from this type of service. How did you get into this? Have a great day! Thanks again.

all they have to do is apply to the site and verify 2 years experience. Not a bad hobby.


Happy Holidays!

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