nestthermostat-c-wire
My old thermostat had 4 wires. I replaced with a Nest thermostat. At times the AC condenser is running but the furnace blower is not running. Found other with this and they said need to add common wire. I do have an extra wire just not sure where to connect it. there is a C terminal on the furnace, just not sure if its to be used for the thermostat or not, it has 1 wire connected already. attached is a picture. Furnace is a Kelvinator g6rc-080c:
C terminal.C terminal.C terminal with the new C wire, and the other end of the scrap bit of wire.When finished, the two C wires should be connected together, along with the wire that's connected to the C terminal.
This type of connection is known as a "pigtail".
Yes, the terminal at the lower right in the photo is C.
Here's the wiring diagram from the documentation, which I highlighted in different colors.
Here's your wiring, which I highlighted using the same colors.
Best Answer
Simply land your blue wire on the C terminal
Most HVAC control board low voltage terminal blocks are designed to terminate 2 wires under each terminal, as was done with the Y terminal on your control board. So, turn off the furnace, loosen the screw on the C terminal, land the blue wire there (after stripping the end back if need be), tighten the screw back down, turn the furnace back on, and you'll be good to go.