Yep. Luckily that is clearly marked at the breaker box
Speadie,
Hi! I think I have a similar issue but I’m not sure how to fix it. Wondered if you had some thoughts. I’ll post my original wiring and my Wyze thermostat wiring but can only do one photo per post right now. Any help is greatly appreciated! Let me know if you need more info or photos. Thanks!
Yep. you’ll need to find the splice location for Y- Follow the thermostat wire out of the air handler back until you find it. It should go out to your compressor on yellow and come back on blue. When you find the splice, make a note of what color wire is connected to each of the yellow and blue wires- you’ll need to run a new wire pair back to the air handler. The wire that is currently attached to yellow should be connected to Y at your furnace, The wire that is currently attached to blue should be connected to C at the furnace. The blue and yellow wires should be attached together at the splice point so that they form a continuous wire, and the wire that is currently in C at your furnace should be switched to Y at the adapter.
Here’s a wider shot of my furnace. The four color wires are from a brown wire that comes from the white box on the left side. Not seeing any spice.
Follow that brown wire until you find the splice. It wont be real close to the furnace, but it usually follows the insulated copper lineset that connects the outdoor A/C compressor to the indoor evaporator coil.
Edit: Do you have a heatpump? Normally that’s the reason for this box.
I don’t have a heat pump. Maybe there was one at one time?! The brown wire goes into this box. I believe one of the larger white wires at the top goes to the thermostat.
Open the box, the splice is inside. One of those white wires goes to your thermostat, one goes to your air conditioner. If the board is still hooked up, take a picture and post it here and I’ll tell you how to wire it up.
You might end up putting the adapter in that box instead of in your furnace, depending on how it is wired.
Bingo! Lots of splices inside. I tired getting a few pics to give you a good view. I really appreciate all your help!!
Go back to your thermostat and pull on the wire a bit- are there more wires in the wall that you could use to avoid needing the C adapter?
Yes, there are four other wires wrapped around the wire.
Take the blue wire and connect it to C on your wyze.
Then unwrap the blue wire in that box that comes from the left bundle of wires and add it to the wire nut that has the red and blue wire in it. Remove the C adapter from the furnace and tell the wyze app that your “old thermostat” has a R,W,Y,G, and C wire during setup.
On the furnace board white goes to W, red goes to R, blue goes to C, and green goes to G, just as it was originally wired.
This wire nut is where you want to add the blue wire from the thermostat bundle of wires to. It will have 3 wires in it when it is wired properly (2 blues and a red).
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It worked!!! The outside AC unit turned on and the heat still works as well. You rock! I can’t thank enough for all the time and support you have provided. I am truly grateful for all that you have done!! 
Be well and thank you once again!
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Well I spoke too soon. Just realized that when the heats on the AC unit also turns on! Ugh!!
I factory reset the thermostat and I think that fixed it. It appears to be running normal now. I’ll monitor over the next few days but temps dropped today so will be running heat again for awhile. Thanks!
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Yes, that is because it thought you had the C adapter hooked up, but you fixed it when you reinstalled it and told it you had a C wire.
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Speadie. This didn’t work. The blower kicks on but the compressor never does. Maybe switch the red/white?
From OP
You might have blown a fuse in your AC running it with the heat all winter long…