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M Oglesby
M Oglesby, HVAC Technician
Category: HVAC
Satisfied Customers: 2038
Experience:  Universally Certified HVACR Technician
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I have a LEnnox pulse 21 G2103-60-1 that wont start the heat

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I have a LEnnox pulse 21 G2103-60-1 that wont start the heat cycle. the old thermostat clicked (I replaced the thermostat as a troubleshoot step) but the furnce wont kick on. the fan comes on, I was thinking a dirty ignitor switch - thoughts? how easy for DIY?

M Oglesby :

Remove the thermostat cover. You should see a R terminal W terminal Y terminal W terminal

M Oglesby :

Remove the wires from the R and W terminal and twist them together.

M Oglesby :

Go to the furnace and observe the ignition start up process. The inducer fan motor should come on first.

M Oglesby :

Let me know if it comes on or not.

Customer:

Thanks, XXXXX XXXXX Rh and W were not previously tied together, why would this happen?

M Oglesby :

They should not be tied together.

M Oglesby :

This is a troubleshooting method to bypass the thermostat.

Customer:

oh, okay, I will turn off breaker, then try this, BRB

M Oglesby :

ok

Customer:

hello

Customer:

I did observe the furnace "click on" to deliver heat, but I noticed a low hum sound.

M Oglesby :

It sounds like you inducer fan motor is not coming on.

Customer:

ok

M Oglesby :

Use a voltmeter to see if the inducer fan motor is receiving 120 volts.

Customer:

what do i do then?

Customer:

how do we detemine if that is the issue?

M Oglesby :

If it is, and the inducer fan motor is not coming on, then the motor is bad.

Customer:

hmm that sucks. is there another troubleshooting step we can do to focus on the issue before we resolve that is it?

M Oglesby :

No.

M Oglesby :

That is it.

M Oglesby :

Then inducer fan motor must come on first.

M Oglesby :

If it does not come on, then nothing is going to work.

Customer:

what does a replacement usually run? is it a DIY thing?

M Oglesby :

Yes it is a do it yourself thing. They usually run about $150

Customer:

dang.

Customer:

just go to Home Depot?

Customer:

how do I know the model, etc.?

M Oglesby :

But first you have to use the voltmeter to see if it is receiving 120 volts. If it is, then the motor is bad. If it is not, then the control board is bad. You cannot get one from Home Depot.

M Oglesby :

You will have to get the model number and serial number of the furnace.

Customer:

ok, thanks.

M Oglesby :

You are welcome

Customer:

so find someone with a voltmeter, check to see

Customer:

if what is receiveing 120v? what do we hook it up to?

M Oglesby :

Please hit ACCEPT if you are satisfied with this service. Thanks!

Customer:

well hang on, please

M Oglesby :

There are two wires hooked to the inducer fan motor.

M Oglesby :

A black and white wires

M Oglesby :

Remove the wires from the inducer fan motor and hook the meter leads to these two wires

Customer:

ok, so if that is NOT getting 120v we need a new board, if it is, then a new motor?

M Oglesby :

That is correct.

Customer:

okay, thanks, XXXXX XXXXX give it a go.

M Oglesby, HVAC Technician
Category: HVAC
Satisfied Customers: 2038
Experience: Universally Certified HVACR Technician
M Oglesby and other HVAC Specialists are ready to help you
Customer: replied 5 years ago.

Hello

 

I do not see any white and black wires on the furnace unit. I have attached an image to show you what the unit looks like. Any further assistance is appreciated.

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Can you send me a picture of the lower portion of the furnace?
Customer: replied 5 years ago.
I did not even realize that bottom panel comes off! Attached. Looks like there is a brown wire and a brown and white wire.

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that is not the blower you need to be checking. The one at the bottom is the blower motor. You need to check the inducer fan motor or exhaust fan motor. It has a rubber hose attached to it and connects to a round pressure switch. The wires may not be black and white, but is only has two wires attached to it. Check them to see if they are receiving voltage. I cannot see the inducer fan motor on your photos.
Customer: replied 5 years ago.
Thanks, what about the silver thing in the upper left corver of the first pic?
That silver thing is the pressure switch. Is the green light flashing in a pattern? Such as 1 flash pause, 2 flash pause, etc...?
Customer: replied 5 years ago.

HI, thank you!

 

No, the LED light is solid green in the box just below it.

Do you have the R and W wires twisted together at the thermostat?
Customer: replied 5 years ago.
I do
The light should be flashing. This is a indication of control board failure. I advise you to have a tech come out and verify then repair.
Customer: replied 5 years ago.
Will do, thanks.
no problem
Hello,the lit light on that control shows normal operation. The issue is likely inducer related. If the control is solid, verify if fan is running by feeling for air at exhaust. If it is not check voltage to inducer..also check limits as they will activate lockout also. There is troubleshooting in the back of this manualhttp://www.cozyparts.com/Lennox-Parts/forum/Lennox_service_manual/Furnaces/G21_GSR21_10-01-2001.pdf
Customer: replied 5 years ago.

Thanks Billy

 

When I turn on the fan, there is air blowing through the floor vents. I would like to check the inducer, but I cannot find it! Ha! I will check the manual for the inducer and "limits"

The manual will help you...the plastic pipes carry the exhaust fan air..so they will lead to it.

 

also look at component placement in manual.

 

 

Customer: replied 5 years ago.
Thanks, what about the reset button on the blower - is that of any value?
Customer: replied 5 years ago.
Is the inducer the same thing as the purge blower? I just dont see an inducer on the unit component diagram
Customer: replied 5 years ago.
This is bad, right? Hopefully there is more data to be gathered here!

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the inducer motor is the same as the purge blower. According to the last picture that you sent, it is not receiving voltage. This is a indication that the control board is bad.
Customer: replied 5 years ago.
But control board light is green
But it is not sending power to the inducer motor on a call for heat. That means it is bad.
Customer: replied 5 years ago.

Thanks

You are welcome.