# Lennox Furnace Dead



## fabrk8r (Feb 12, 2010)

Does anything happen when thermostat calls for heat? Does inducer fan start?

If both LEDs on circuit board are out there must not be power at the board. Have you checked the low voltage fuse?


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## Ron6519 (Mar 28, 2007)

fabrk8r said:


> Does anything happen when thermostat calls for heat? Does inducer fan start?
> 
> If both LEDs on circuit board are out there must not be power at the board. Have you checked the low voltage fuse?


The furnace is silent when the thermostat is raised calling for heat.
The fuse is intact.
I'm going back with a meter to see if there's voltage coming out of the transformer. I'll also check the fuse for continuity in case it's not connected at an end.


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## gregzoll (Dec 25, 2006)

I would try connecting the thermostat with a short stub of wire, right at the furnace, and see if you can get a call for heat. It is also possible, that the thermostat is fubar.


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## Ron6519 (Mar 28, 2007)

gregzoll said:


> I would try connecting the thermostat with a short stub of wire, right at the furnace, and see if you can get a call for heat. It is also possible, that the thermostat is fubar.


I tried another thermostat an hour ago, no luck. I checked the transformer and had no reading coming out to the mini breaker on the low voltage side. I'll try replacing that. After that, it's a service call.


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## Marty S. (Oct 31, 2009)

Do you have high voltage at the transformer terminals of the control board?


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## Ron6519 (Mar 28, 2007)

Marty S. said:


> Do you have high voltage at the transformer terminals of the control board?


There is 110 volts on the line side of the transformer.


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## Doc Holliday (Mar 12, 2011)

Ron6519 said:


> There is 110 volts on the line side of the transformer.


 
Turn the stat to Auto and Cool and drop the temp. If the cooling works then it's not the transformer.


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## Ron6519 (Mar 28, 2007)

Doc Holliday said:


> Turn the stat to Auto and Cool and drop the temp. If the cooling works then it's not the transformer.


Will this just operate the fan in the furnace? He has no central A/C.


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## hvactech126 (Nov 11, 2010)

If you have no LED lights that should be flashing slow without a call for heat, then you either have no 24V or you have a bad control board. WIth a call for heat the LED lights should flash fast.


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## Doc Holliday (Mar 12, 2011)

Ron6519 said:


> Will this just operate the fan in the furnace? He has no central A/C.


Put stat to fan on. If anything works than low voltage is present. Tyranny should be good then.


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## Doc Holliday (Mar 12, 2011)

Transformer gives stat control voltage so if any or one call works tyranny is good.


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## hvactech126 (Nov 11, 2010)

Doc Holliday said:


> Put stat to fan on. If anything works than low voltage is present. Tyranny should be good then.


How do you know that G is wired?


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## Doc Holliday (Mar 12, 2011)

hvactech126 said:


> How do you know that G is wired?


How much wood could a wood chuck chuck if a wood chuck could chuck wood?


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## Doc Holliday (Mar 12, 2011)

Tech, I don't know.


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## Master of Cold (Aug 7, 2011)

Welcome to internet diagnostics 101.

Never assume anything...

Just because they have a meter, doesn't mean they know how to use it.

Do not be influenced by what they "think" it is. If they knew, they wouldn't be here.

Pay attention to what you are not told.

When all the techs agree, its the wrong answer.

People tend to focus on what the last guy out there did.
If this were relevant, replacing my transmission will fix my flat tire.

People tend to focus on what the last guy out there did.
If this was not relevant, we wouldn't have call backs.

I am the Master of Cold. If I goof up your furnace, your on your own...


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## Doc Holliday (Mar 12, 2011)

My two cents would be Master is great. So is tech amongst others.
PS, you and are is you're.


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## Doc Holliday (Mar 12, 2011)

I wasn't kidding, Master is one of the few I learn from come hvac. English composition not so much.


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## Master of Cold (Aug 7, 2011)

My composition...
Oh well 
At least their are not any spelling nazi's around.


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## Master of Cold (Aug 7, 2011)

If the transformer is bad make sure you get an autobot, and not a decpticon...


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## Ron6519 (Mar 28, 2007)

So the problem is solved. Actually 2 problems. The transformer was bad and so was the board. Once the tech switched out the transformer( I don't know what this means. "...make sure you get an autobot, and not a decpticon...") , the unit livened up, but no heat. Glow stick didn't glow. He checked all the switches were working properly, with the Lennox tech on the phone guiding the procedure. He picked up the new board and once installed, the furnace fired right up.
Seems the house had a storm last year that fried a TV and the cable box. I'm thinking this is when it happened.
Tomorrow we put in a whole house surge protector.
Thanks for the input.


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## Master of Cold (Aug 7, 2011)

The autobot thing was from the Transformers movie..


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## Ron6519 (Mar 28, 2007)

Master of Cold said:


> The autobot thing was from the Transformers movie..


Okay, ...humor. 
I get it now.


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## Doc Holliday (Mar 12, 2011)




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