Forum Discussion
BFL13
Nov 17, 2019Explorer II
"The 2 blue wires----ONE is output 12 volts to the tstat OR the AC control board. The OTHER BLUE wire is the down 12 volt supply from the Tstat OR the AC control board to tell the furnace to start a cycle"
So when the single white wire from the Tstat is "furnace" that is the "down" wire and it is "energized" (Tstat manual's term) with call for heat. If the Tstat has that red 12v wire, then it would be like the live "up" blue wire, and the Tstat makes the red and white connect to "energize" the white down wire?
So in that case what would happen with the furnace's live "up" blue wire? Just cap it off? Join the "down" blue wire to the "down" white wire is all that is needed?
So when the single white wire from the Tstat is "furnace" that is the "down" wire and it is "energized" (Tstat manual's term) with call for heat. If the Tstat has that red 12v wire, then it would be like the live "up" blue wire, and the Tstat makes the red and white connect to "energize" the white down wire?
So in that case what would happen with the furnace's live "up" blue wire? Just cap it off? Join the "down" blue wire to the "down" white wire is all that is needed?
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