I know this question gets asked all the time but I've spent hours staring at forums as well as my furnace and at this point I'm desperate. I just bought a nest thermostat that needs a C wire connection. My furnace doesn't have a C wire slot to plug in the wire and I'm trying to find out what I need to connect this C wire coming from my thermostat to.
This is a strange assembly and is on the wall across from my furnace. I'm assuming the blue wire coming from the thermostat not connected to anything is the C wire. Only the red wires have voltage.