Before installing a new Learning thermostat, here are pics of my wiring just in case someone sees something unusual or incompatible.
Things I noted (they may be normal after all, since i 've never worked HVAC):
- Replacing an old mercury blob Honeywell thermostat. There's a jumper wire in old thermostat connecting its Y terminal to somewhere on the physical Heat/Off/Cool switch. I assume this is just part of this thermostat's control of the cooling/heating physical switch and I will not have to worry about it on the Learning thermostat. I will connect Y-wire to matching Y connector as per default installation instructions.
- C-wire (blue) is present but was never connected to both thermostat and furnace control board's C terminal- it was not needed. Will strip both ends and connect to corresponding C terminal in furnace and connector in thermostat. Red (R), white (W), green (G), and yellow(Y) wires seem to be connected properly on both ends.
- There's a brown wire that's not connected on both sides and is next to unused C-wire (blue). Will assume as spare and leave this alone.
- Two wires (red and white) from a brown sheathed cable that is connected to the outside unit of the AC connects to the C and Y terminals of the furnace control board. I assume this is normal part of the wiring/controls for the cooling. Unless I hear otherwise, I will leave them connected as is. The C terminal will just have the additional blue wire i'm connecting to it after I install the learning thermostat.
Help not needed anymore.
I went ahead with my plan, stripped and connected C-wire on both ends, installed like normal, connected to wifi to update firmware, and everything seems to work well. Installed Nest app after installation, logged in with Google account and it synced flawlessly with Google Home.
