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BillyHvac
BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 22420
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my lennox furnace model #V810A1012 will not start up. I have

Customer Question

my lennox furnace model #V810A1012 will not start up. I have a pilot light, and the thermostat is commanding heat
Submitted: 8 years ago.
Category: HVAC
Expert:  BillyHvac replied 8 years ago.

Hello RC,

 

Does your thermostat have a "fan on" switch? If so what does the furnace do when you turn the fan on? By the way...this is for info only so no charge to get info.

 

Billy

Customer: replied 8 years ago.

It has a fan on or an "auto" switch, but the furnace will not cut in on either setting

Expert:  BillyHvac replied 8 years ago.

Ok, this means there is no power to the furnace, or a bad trans former. Can you check to see if the breaker is ok or maybe a fuse in the switch on the side of the furnace? Sounds like we just need to get power.

 

Billy

Customer: replied 8 years ago.

I have two furnaces on the same breaker, and it looks like the same switch. This is a new house to me, built in 1980, and one furnace looks newer than the other.

 

I have a DVOM, maybe I will try to find out if there is power to the motor

Expert:  BillyHvac replied 8 years ago.
Is the furnace old enough to have a mechanical "fan switch" in the furnace with the white button that you can push in for fan?
Customer: replied 8 years ago.

Yes, it has both

 

Expert:  BillyHvac replied 8 years ago.
Try that switch because that one is straight 120 volt and does not rely on a transformer. If it starts the fan, you have 120 volt but not maybe not 24v thermostat voltage. If it does not work odds are you have no power to unit.
Customer: replied 8 years ago.

I tested the switch..ok..checked the box it feeds to..connectors are fed power, and it appears to be ok to there. I could not access the wire at the motor, but the wiring looks good. I tapped on the motor to see if maybe the brushes were sticking, but nothing

 

Expert:  BillyHvac replied 8 years ago.

Ok, so the blower started with the fan switch in the furnace?

 

If you feel comfortable with it, I can tell you how to proceed.

 

Billy

Customer: replied 8 years ago.
No..the blower did not start..there is power to the wiring to the motor, but it will not start
Expert:  BillyHvac replied 8 years ago.

Ok,

 

but the burner should come on and run, then after the blower does not run it would shut off on limit.

 

Can you remove the cover on that fan/limit switch and look at the round dial with numbers on it?

Customer: replied 8 years ago.
Is that on the side of the motor?
Expert:  BillyHvac replied 8 years ago.

If you take the top cover off where the burners are, there should be a silver box about 2"x3" .

 

Is the furnace top hot?

Customer: replied 8 years ago.
No..the only fire is the pilot light
Expert:  BillyHvac replied 8 years ago.

Ok, lets go over what we have...

 

pilot is lit

thermostat is set for heat and turned up

furnace has power, but fan will not turn on by fan switch

motor has power to it.

 

Anything else you notice? Does the other furnace work?

Customer: replied 8 years ago.
The other furnace works well. I don't see anything unusual.
Expert:  BillyHvac replied 8 years ago.

Well, I think you are in the area of needing to troubleshoot with a meter.

 

Verify (with meter) 120 v into furnace.

Verify 24 v from transformer

verify blower motor operation

 

It sounds as though your blower motor is bad from the information you gave me.

 

 

Billy

Customer: replied 8 years ago.

I have verified 120 volts to the motor

I have 28 volts from the transformer

I expected the motor was the problem..Does that look like it? Is 28 volts from the transformer ok?

Expert:  BillyHvac replied 8 years ago.

28 volts is great.

 

If you have 120 to the motor, and it is not running, you have a bad blower motor.

 

Billy

Customer: replied 8 years ago.
Thanks for your help.
Customer: replied 8 years ago.
Send one more reply....I cannot find the "accept: button
Expert:  BillyHvac replied 8 years ago.

good luck, I am available for follow up.

 

Billy

BillyHvac and other HVAC Specialists are ready to help you
Customer: replied 8 years ago.

Thanks for your help. I did not have the knowledge to confirm the problem, and you can spend a lot more on guesses than you save.

 

I am a mechanic, and so I know the value of a good tradesman.

Expert:  BillyHvac replied 8 years ago.
Thank you, XXXXX XXXXX customers like you.

Billy

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