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BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 21997
Experience:  Endorsed for unlimited heating, cooling, oil burners, boilers, refrigeration, hydronics
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The main blower on my furnace isn t working. Just humming.

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The main blower on my furnace isn"t working. Just humming. I looked up a forum and another had the same problem. Not sure if the unit was humming though. The expert had him check his thermostat by jumpering the red and green wire on his thermostat. That helped him, so I tried that and the fan still didn't turn on? Any ideas? I have a Carrier Weathermate 8000TS unit.





Do you have the model number of the 8000ts?



Customer: replied 5 years ago.

Thank you ,


Have you been able to inspect the capacitor to see if it is bulged or leaking oil?



Customer: replied 5 years ago.
I'm assuming the capacitor is the part attached to the side of the blower housing with two brown wires? It looks normal size and there is no oil below it.

Thank you,


Do you have a volt meter for testing?



Customer: replied 5 years ago.
Yes I do. Not very good at using it, so I may need a little guidance.


First have bottom door off to furnace with safety switch taped down. Then turn thermostat to on position. Then on circuit board locate black wire from blower motor and see if 110v is present, also try red wire.

Customer: replied 5 years ago.
just to make sure I'm using the volt meter properly should I remove the black wire from the circuit board terminal and touch one of the volt meter leads to the connection on the circuit board and the other to a ground?

You are correct.


Test meter in a known working 120v outlet to test.



Customer: replied 5 years ago.

tested the volt meter on a 120v outlet. Tested black terminal- did not get any voltage.

tested red terminal- got 120v


Thank you,


And while 120v was present the motor was still not running?



Customer: replied 5 years ago.
yes. that's correct



Ok, now when you hear motor humming and it should be running, spin the fan wheel by hand and tell me it tries to start or not.



Customer: replied 5 years ago.

turned on, rotated fan by hand, now fan is running- do I need to follow up on the blower motor?


Replace the capacitor.


If fan ran with a hand spin it is moist likely capacitor.



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