# Control Board Question



## Not-a-Rookie-Not-a-Guru (Nov 1, 2014)

Posting again with different title because it has really gotten totally away from the original question.

Fan and AC work as expected but no heat on a 2001 Armstrong HVAC Model # PGE10B42D100A-3 with a Honeywell Lennox Armstrong Ducane Control Circuit Board 1097-502-I 1097-83-503A

I had time to really diagnose it today. It's not turned off at the switch nor has a fuse blown. I even decided to update the Thermostat and get rid of the old mercury switch. I get the expected currents coming from the thermostat to the unit in each mode, fan, AC and heat. The code light constantly blinks "Normal operation, calling for heat" (That would be constantly blinking 2 blinks per second, no pauses) when there is any power on the unit. No fan running, fan only running, AC on and finally heat on but when you go to heat, the Inducer motor never kicks on. This caused me to think blown control board. I turned the power off and waited a few minutes to assure no residual power might be lurking anywhere and pulled the board. If you look at the attached .jpg (not exactly my board, it's similar but not exact), in the bottom right hand corner of the board are 4 blue Capacitors or resistors (never knew how to tell them apart). On the back of the board running from one side of the capacitor/resistor to the other of the two middle ones was a heavy dark streak. It looks like an electrical short. So I am sure that is why I am getting the behavior I am getting from the unit.* I just wonder if the board just blew or might there be something that caused this?* All constructive input will be appreciated.:help:


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## kok328 (Nov 1, 2014)

Did the unit work with the old thermostat?

Are you getting power to the inducer motor when calling for heat?


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## Not-a-Rookie-Not-a-Guru (Nov 2, 2014)

kok328 said:


> Did the unit work with the old thermostat?
> 
> Are you getting power to the inducer motor when calling for heat?



No it didn't  and no power at all.


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## Not-a-Rookie-Not-a-Guru (Nov 5, 2014)

So now I am at a total loss. Brand new controller board installed. Even if I have cool up to 80 on the thermostat and heat down to 60 (it's 68 here now) i get normal operation calling heat. I am at a total loss and would appreciate any questions or suggestions.


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## nealtw (Nov 5, 2014)

Any chance a bad wire to the t, stat. You could do a continuity test on the wires or bring the t,stat to the furnace and wire it up and see if that works.


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