# Payne furnace -- Error Code 12



## orcaboy (Mar 6, 2011)

I have a Payne furnace that sometimes flashes an error code 12. A tech replaced the circuit board earlier this week and it seemed to be working fine.

It's now flashing the error code 12. After the furnace turns off, the red light doesn't flash. Only flashes when it's trying to run properly.


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## how (Feb 26, 2011)

Check your manual or the index info (sometimes glued on inside of the furnace door) or google for what that 12 code means. Some codes just say that you've got power and everything is OK.
Do you have any other indication of a problem?


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## hvactech126 (Nov 11, 2010)

Fault Code 12 indicates a power interruption on the furnace powered up during a call for heat. If this code is present, verify that the blower runs for ninety seconds before the furnace starts a normal heating cycle.
You sure it is not a 21 instead?
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## orcaboy (Mar 6, 2011)

Based on the description of how to read the error code, it's a 12.

The furnace kicks on, runs and I can see the orange glow. The burners then kick on and I can see the blue flame. Just before the fan blower starts to run, the burners turn off and the 12 code flashes until the unit cycles off. Once it's off, the light remains red and does not blink.

It doesn't do this all the time.


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## orcaboy (Mar 6, 2011)

Also -- the furnace is keeping the temp in the house steady, even when I've been getting the error code. The air coming out of the vents seems a little cool, but the house isn't cold.


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## hvactech126 (Nov 11, 2010)

Code 12 only comes on when the furnace is powered off and the stat is calling for heat and the furnace was powered on.


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## beenthere (Oct 11, 2008)

Sounds like a loose line voltage connection somewhere.


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## orcaboy (Mar 6, 2011)

Thanks ... looks like I'll be calling for another service call.

Meantime, any suggestions on things I could check myself?


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## beenthere (Oct 11, 2008)

Line voltage wire connects inside and outside of the furnace.


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## orcaboy (Mar 6, 2011)

I'll check things out and will post results.

Anu chance I could have a bad thermostat?


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## beenthere (Oct 11, 2008)

A low voltage thermostat is not going to cause a loss of line voltage power.


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## orcaboy (Mar 6, 2011)

That's what I figured, but was hoping for a quick, easy and inexpensive fix.


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## orcaboy (Mar 6, 2011)

Still working through the issue. Tech replaced a relay, checked all electrical connections, ground, etc.

Unit still throws a 12 code at times, but still very hit-and-miss.

Was able to trigger the 12 code by lowering thermostat temp while burners are fired but before the fan kicks on.


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## beenthere (Oct 11, 2008)

orcaboy said:


> Still working through the issue. Tech replaced a relay, checked all electrical connections, ground, etc.
> 
> Unit still throws a 12 code at times, but still very hit-and-miss.
> 
> Was able to trigger the 12 code by lowering thermostat temp while burners are fired but before the fan kicks on.



That shouldn't give that error. Loose connection somewhere, or a cold solder joint on the board.


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## how (Feb 26, 2011)

I'm doubtfull... "beenthere"

I don't think that when a board is flashing 12 and is replaced by a new board that also starts flashing 12, that a diagnosis of 2 seperate identical cold solder faults is likely. Are you suggesting a 3rd board?

I'd keep looking for that loose connection everywhere. 
Do your house lights flicker occaisionally? I've had hairy diagnostic issues from both a loose neutral at the pole and from another with a loose house ground.
This job used to be simple!


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## heatycooly (Mar 11, 2011)

You have a dirty flame sensor pull it out sand it down you are done


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## beenthere (Oct 11, 2008)

how said:


> I'm doubtfull... "beenthere"
> 
> I don't think that when a board is flashing 12 and is replaced by a new board that also starts flashing 12, that a diagnosis of 2 seperate identical cold solder faults is likely. Are you suggesting a 3rd board?
> 
> ...


Didn't realize the board was already replaced.


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## orcaboy (Mar 6, 2011)

I've already cleaned the flame sensor, so I don't think that's the problem.

The 12 code only flashes after the burners have lit -- the burners will kick off right as the fan begins to run. And it doesn't happen all the time.

I tried lowering the thermostat temp again while the burners were on, and prior to the fan kicking in. Again, the 12 code flashed as soon as the burners went out and the fan started to run.

Lights in the house do not flicker or flash.

It's been suggested to me that it could be a problem with the thermostat, which seems to make sense to me in a way since changing the termostat triggers the code ... techs are supposed to come out today to take another look.


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## hvactech126 (Nov 11, 2010)

Code 12 - BLOWER ON AFTER POWER UP (115V or 24V) - Blower runs for 90 seconds, if unit is powered up during a call for heat (R-W closed).

I've never seen one do what you say, however as I read this code, R &W has to be closed for this code to be produced.


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## orcaboy (Mar 6, 2011)

What does "r-w closed" mean?


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## heatycooly (Mar 11, 2011)

It means you are calling for great


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## heatycooly (Mar 11, 2011)

Heat not great sorry


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## orcaboy (Mar 6, 2011)

After checking and double-checking all electric connections, the breaker box, and numerous switches a new thermostat was installed.

Since then the furnace hasn't been cycling off and on nearly as often, the house is more comfortable temperature-wise and the furnace hasn't thrown an error code.

I've turned the thermostat down after the burners have fired (which previously triggered the error code), and all appears to be working properly.

I will post again if the error code reappears.


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