No C wire on thermostat or furnace


Old 08-21-17, 09:43 PM
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No C wire on thermostat or furnace

Appreciate all the posts already here of which I've read and wanted to make sure I was doing this correctly. Looking to put in a honeywell wifi thermostat as the one there now isn't even programmable. I get most of it but wanted to make sure I can use the Com 24v slot on the Carrier furnace and move the G wire to that location. Next question is what becomes of the wire that was removed from Com 24v - does it just get tied off and not used anywhere else. And then I need to create a jump/link from Y to the now vacant G on the furnace, correct? I see there's already two wires being used on Y and want to make sure it's ok to use a third. Pictures attached. Thanks for any comments, advice, or assistance. Note - I understand this method disables use of fan by itself and only works when system AC or heat is on.
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Old 08-21-17, 09:56 PM
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Welcome to the forums.

It's good you posted pictures. There is currently a white wire on the C terminal and there is a red wire on the Y terminal. If you look.... these two wires are in one cable. That cable goes outside to the condensor. Those wires stay right where they are.

Move blue wire to C. You will now have two wires on C.
Install a jumper wire from Y to G. You will now have three wires on Y.

Be sure to turn furnace off when messin' with the wiring.
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