Furnace Common Wire


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Old 12-07-14, 12:09 AM
J
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Furnace Common Wire

The old circuit board for my furnace had a relay that was sticking so I got a new board that doesn’t have a ‘C’ connector (my old board did have a common wire hookup right on the board). The new board works fine but I’d like a C line to wire to my thermostat (my thermostat is cycling my furnace fan off/on and causing the furnace to click and not turn on the heat). Where can I connect a common wire to this new board? The board model number is B1809913.

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Can I draw from the transformer?

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Or is there a spot on the board? Or does this board not support a common wire? According to this diagram for my board:

http://www.icmcontrols.com/ProdImages/ig_LII318-2.pdf

the molex connector in the middle has a C connector, can I somehow draw from that connector?
 
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Old 12-07-14, 09:06 AM
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Welcome to the forums.

Many Goodmans, yours included, ground one side of the secondary of the transformer to ground and that is the Common connection.

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Old 12-07-14, 10:59 AM
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Great, thank-you! So I can connect to that ground to the 'C' in my thermostat and it will provide a constant 24V for power? And I can test the voltage with a multimeter from C to R? I appreciate the help.
 
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Old 12-07-14, 11:11 AM
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And I can test the voltage with a multimeter from C to R?
Yes.... you can check for 24vac there.
 
 

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