Thermostat c wire or adapter questions

Ok so I don’t accidentally disable the furnace on Christmas Eve during the coldest weather so far and make my wife really proud… And since I don’t completely understand how the furnace works I thought I’d run this by you guys.

Looks like I have a c post in the furnace but it’s not used for the thermostat. I do have extra conductors, at least at the furnace side, pretty sure they are behind the thermostat also.

Should I just hook another conductor to the c post then report that along with the R. W. G. And Y connection in the app during setup. Or should I install the c adapter?

I luckily found a spare wire in my wiring and i just used it to connect to the c connection in the furnace. Might need a wipedown if theres corrosion.

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Should be able to connect the blue from the furnace to the thermostat.


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That’s what I was thinking but I didn’t know what that other wire hooked to the c lug was for. After some reading I’m pretty sure its just supplying power to the outside unit.

Correct, both C and Y will have 2 wires, one for the thermostat and one for the a/c outside.