Thermostat wiring might need correction

Need help with my wiring. AC fan not turning on consistently. Maybe i did something wrong. Greatly appreciate the help.This is what i have.

1 Like

Couple of things I’m seeing here. first off, the wire from the thermostat to the W connection on the C adapter looks a bit off- the wire appears to go into and then back out of the terminal:
It should terminate inside of the terminal, the end shouldn’t come back out.

Second, and more concerning, the Y connection going to the AC compressor from the furnace terminal strip appears to be shorting to the metal case.

You want that connection to not be touching any grounded metal parts. Your furnace must not have a fuse, or it would have blown from that short circuit.
Trim that white wire back a bit and reconnect it to the Y screw, this time making sure it’s not touching any other metal parts, or other terminals.


Thanks @speadie.

Went back and did them all over. Other than that do you see anything else?

Nothing that stands out. Is it working properly now?

No it’s not. The system will turn on but the ac fan won’t most of the time. It came on this morning before I left for work and kept the house cool. When I arrived home, it was still set to auto, and when it tried to start again to reach 75 degrees, no ac fan.

When you say the fan isn’t turning on, do you mean the indoor blower motor? If so, the insulation on the G wire from the C adapter appears to be under the screw on the furnace board.
While it seems unlikely, this could be preventing a secure connection to the actual core of the wire, thus causing an intermittent connection.

Do you have a blue wire near the furnace board coming from that thermostat wiring? I see one in the wall near the wyze, and if you have one near the furnace, you might not even need the C adapter.

1 Like

When I said fan I meant the a.c. compressor outside. Yes there is a blue wire on both. They were wrapped around both wire bundles and not connected to anything.

1 Like

Well, you can eliminate the C adapter as the source of the problem if that blue wire is contiguous. You’d need to reset the wyze thermostat and reinstall it, telling it that you have the following wires on your old thermostat: Y, C, G, Rc, W.
You’d remove the C adapter, connect the wires where they originally went (green to G, Yellow to Y, white to W, and red to R) in addition to connecting the blue wire to C on both ends, and connecting the Green wire to G on the wyze.

If that fixes the issue, then the short on the Y wire on the furnace terminal probably burnt the contacts in the Y relay in the C adapter.

If removing the C adapter doesn’t fix the issue, you might need to call a service technician. With the issue being the outdoor compressor unit, and that arcing to ground on the Y terminal, I’d be worried that the contactor in the ac compressor might be going bad.


Removed the C adapter and wired everything back up. Now I’m getting this…

What wires did you tell it the “old thermostat” has?
you should have told it Y, C, G, Rc, and W.
If you did that, try skipping that screen. It might not be detecting the wire properly. If you click “try again” a few times, it should eventually let you skip.

I told it those exact wires. Even after skipping nothing is turning on. Did a reset and it’s still saying the Y wire is missing.

1 Like

It sounds like that short circuit might have caused damage to the contactor in the outdoor ac unit then. If you run a jumper wire from Y to R on the furnace, does the outdoor compressor/fan kick on? If so, then the wyze thermostat is defective. if not, then either the wire to the outdoor AC is defective, or the power to the AC unit is off, or there’s something wrong with the AC unit (tripped fuse, dead capacitor, or bad contactor all spring to mind as likely possibilities).

1 Like