Connecting c wire to old furnace

Joey Huffer
2 months ago
last modified: 2 months ago

I just installed a nest thermostat and need to hookup the c wire inside the furnace. I read where you need to connect the c wire to the secondary wire on the 24v side of the transformer. There are 2 yellow wires leaving the 24v side of the transformer. 1 wire goes up the panel and connects to a white wire (top of last pic) that is going out to the ac unit outside and the other yellow wire connects to a blue wire which is connected to the red thermostat cable (very bottom wire nut on last pic). From the looks of my wiring diagram, I believe I just need to connect the unused c wire to the wire nut with the yellow and white cable but I’m not 100% sure. Any help would be awesome. enter image description here[

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