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BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 22312
Experience:  Endorsed for unlimited heating, cooling, oil burners, boilers, refrigeration, hydronics
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I have fire.. exhaust fan runs but main fan does NOT run, o,

Customer Question

I have fire.. exhaust fan runs but main fan does NOT run
JA: I'll do all I can to help. How long have you been dealing with this?
Customer: o
JA: Do you plan on doing the work yourself?
Customer: Looking into it first
JA: Anything else we should know to help you best?
Customer: Just replaced filter
Submitted: 1 month ago.
Category: HVAC
Expert:  BillyHvac replied 1 month ago.


My name is Billy.

This generally caused by 2 different options.

Motor gets 120v but does not run = bad motor

Motor does NOT get 120v = bad circuit board

Do you have a way of checking?

Customer: replied 1 month ago.
Motor tries / hummus to start.
Expert:  BillyHvac replied 1 month ago.

Thank you...while it hums...try spinning by hand...tell me if it


tries to start

spins and stops

feels very stiff to turn

Customer: replied 1 month ago.
I can hear& see the exhaust fan kick on. Access to the circulating fan ?
Expert:  BillyHvac replied 1 month ago.

the main blower that pushes air through duct is what we need access to.

Do you know where this is?

Customer: replied 1 month ago.
Must be behind the wall. On the bottom where air enters and is forced up through the heat exchanger
Expert:  BillyHvac replied 1 month ago.

will you be able to accesss?

Customer: replied 1 month ago.
Well guess I need. to find the resolve. Being the big boy I am they sure find the smallest corner to put it in.
SO, The cold air return is on the bottom of the unit with the filter on the outside just as it enters the Unit. I must assume that the motor and fan are inside there in the unit. I looked for an access door "NOT finding one" so a couple of screws and a panel should open for viewing. Right?
Expert:  BillyHvac replied 1 month ago.

can you post a picture of the unit? Or a model number and I can direct

Customer: replied 1 month ago.
USA 072 NH3RSER.###-##-####
Expert:  BillyHvac replied 1 month ago.


this is the one unit I really do not like working on....they hid the blower behind the front assembly.

I actually had one where we had to remove the unit. I am not one to steer away a do it yourself project, but this one may be best for a tech...

Customer: replied 1 month ago.
Pretty standard for the life I live. Wasn't trying to sound stupid at the beginning butt. Plumbing is in the blood of the family and I do mechanical stuff daily it ain't going to be fun but here I go.
Expert:  BillyHvac replied 1 month ago.

all I can say on this patience goes a long way...

I wish you the best.


Customer: replied 1 month ago.
OK, The motor appears to be mounted inside of the fan. The FAN spins and moves freely. there is a Capacitor right in front of me. Thinking positive here !! could this be an issue?
Expert:  BillyHvac replied 1 month ago.

yes very possible....If the motor starts up while energized with a hand is capacitor.

Customer: replied 1 month ago.
Well the fan spins freely when unit is not running. Jump the safety switch and ran it through a cycle tried to jump start the fan in the squirrel cage moved but it was tight the motor is located inside of the squirrel cage telling me it is a direct drive system it shows signs of being the motor and not the capacitor by doing this. Going to be a b**** to get this housing out but it's got to be done
Expert:  BillyHvac replied 1 month ago.

you are correct..if tight when energized it is a bad motor.

Good luck!


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