# Furnace has burn smell and blower motor doesn't start



## harleyrider (Feb 20, 2007)

marcusal6 said:


> I have a Lennox 80UHG 3/4 - 100A-2
> 
> Problem: Thermostat calls for heat and the whole cycle starts up with the inducer runs, igniter lights up and flames burn for about a minute or so...usually the blower motor fires up and blows the heat thru the house, but the blower never comes on (I have had the blower motor tested and the capacitor too...both work and the fans spins freely with no issues) then shortly after it shuts off and give an error code LED1 (Slow Flash) LED2 (ON) and the description is Primary or Secondary Switch open. When the blower fan usually comes up I hear a click but nothing happens. The Metal plate that has the circut board mounted to it also has a separate bulky thing with several wires coming out that seems to hum pretty loud and I never remember hearing it before before and after the whole start up cycle...also once it shuts off the whole house smells like burnt wood...that seems to trickle out of the vents
> 
> Any Ideas?


You have a bad HFR (heater fan relay) on the main board, you will need to have a qualified lennox tech out to replace the board.


----------



## Doc Holliday (Mar 12, 2011)

What happens in cooling mode or fan on? It could be a bad relay or a bad fan motor/cap.


----------



## harleyrider (Feb 20, 2007)

Doc Holliday said:


> What happens in cooling mode or fan on? It could be a bad relay or a bad fan motor/cap.


 
quote taken from OP:



> (I have had the blower motor tested and the capacitor too...both work and the fans spins freely with no issues)


----------



## Doc Holliday (Mar 12, 2011)

hAiR today, bAld tomorrow.


----------



## Doc Holliday (Mar 12, 2011)

A burn smell is usually the motor. Good luck.


----------



## harleyrider (Feb 20, 2007)

Doc Holliday said:


> A burn smell is usually the motor. Good luck.


I guess you have never seen a circut board that blew a relay off of it? i have seen it a thousand times, can smell it when i pull in the driveway............yeah, im that good :yes:


----------



## marcusal6 (Jan 16, 2012)

Doc Holliday said:


> What happens in cooling mode or fan on? It could be a bad relay or a bad fan motor/cap.[/QUOTE
> 
> the blower motor doesn't run in cool or fan mode...so nothing happens


----------



## harleyrider (Feb 20, 2007)

post a picture of your circuit board..........it will show a fried relay, you will see black soot and smell the cooked relay. we can have 20 or 30 more post about what _could _be wrong in 50 different pretend scenario's if you would like.........


----------



## marcusal6 (Jan 16, 2012)

harleyrider said:


> post a picture of your circuit board..........it will show a fried relay, you will see black soot and smell the cooked relay. we can have 20 or 30 more post about what _could _be wrong in 50 different pretend scenario's if you would like.........


Thanks Harley Rider!!!...I took the board off and you are exactly right...black spot on the back of the board...getting costs for a new one...so far $223 is the only cost I got...the rest of the shops are closed around here...does $223 seem like a fair price?

the board had a label on it for part info...
9840
50A65-120
Lennox
12L6901


----------



## harleyrider (Feb 20, 2007)

yes......thats a good price !


----------



## marcusal6 (Jan 16, 2012)

harleyrider said:


> yes......thats a good price !


New board dropped in and heat is up and running. There is still a slight burning smell coming from the heater at startup...maybe it's just some felt over smell???...not as strong as before. Could there have been another problem in the furnace to cause the short in the relay...I just don't want to burn out the new board... do you have any idea what causes the blown relay? I just want to avoid this if at all possible.

you gave great advice and knew exactly what was wrong

Thanks Again!


----------



## Tator1076 (Dec 22, 2009)

harleyrider said:


> I guess you have never seen a circut board that blew a relay off of it? i have seen it a thousand times, can smell it when i pull in the driveway............yeah, im that good :yes:


Heck I'm better. I can smell it over the phone when I'm talking to the customer. :thumbup:


----------



## how (Feb 26, 2011)

That smell should be a 1/8 th of what it was but it will hang around for a few more days.


----------

