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I have a Coleman DGAA077BDTA that has will not stay lit.

It will light, burn for a few seconds, and then go out as the blower kicks in. The furnace will repeat this process for a while and then kick out a ignition failure code.

I have had out a tech, they suggested that replace the flame sensor, which I have done already. They suggested that the next step would be the control board, and that they would charge 300 for the board plus 4 hours of labor to replace it. I doubt that I'll let them do it when the board costs 1/3 of their price....and that I'm handy with tools and electronics any way.

The circut board has discoloration near the ignitor fuses (i'm assuming that's what they are for), and get really hot during this process.

I have measured the voltage to the gas valve, and it is 14vac before the gas is called and then is 24vac when the gas is called....but cycles back to 14vac after the burner goes out again.

Ignitor works fine. Burner assembly is clean and clear.

I am suspecting the board due to the discoloration on the resistors, and what appears to be erratic behavior of the gas valve. I don't believe that the control board is correctly seeing the flame sensor still...

Should I be suspecting the gas valve too?

Thanks for any help in advance.

Well I figured out the problem, and it wasn't the furnace itself.

I had checked the roof cap once before, but I had not removed the top cover.

While checking to see if the gas orifice was plugged, I kept hearing this clickity click periodically which sounded like birds walking on a metal roof. But each time I'd rush out the back door to see if there were really birds in the roof vent, I'd see nothing. So I got wise and left the back door open and quitely walked to the back deck and sure enough I saw two birds going in and out of the roof vent.

So out came the ladder once again, and this time I revoved the top cover, and found a huge birds nest that was 18" below the roof line (far enough down to not be able to see it with out removing the cover). I ended up having to fully remove the stack to clean out all of the nest that ran all the way to the top of the furnace.

Glad I figured this out before dropping $250 on a gas valve and control board. It was bad enough to have already paid $80 for a flame sensor and 1 hour of tech labor. Guess I have a spare part for the furnace now.

Thanks for the wonderful site!

Hi,

That's great, glad you resolved it. As for those who came out and wanted $300 for board and 4 hours labor, they're a lot of things, tech isn't one of them though.


Boards are $100 to $200, may can be repaired and not replaced and take all of 10 minutes to replace.


Not to mention they missed the nest.


A flame sensor ~may~ not sense flame due to nest reducing combustion air which means low or no flame. Not big and hot enough to sustain when blower kicks on.


My apologies for our trade, got to watch for the hackers and rip-off artists out there.


Take care and best wishes,
Robert