Thermostat wiring - Can't find C terminal on board

Hello everyone

I have a 20 year old TRANE XL 1200 Gas/Electric Pack system in good working condition.

I followed the guide but could not find the C terminal to connect the CWA to

Current thermostat wiring - blue wire disconnected

I’m sorry about the external link below but the system would not allow more than one embedded photo. Full panel and wiring diagram included.

Thermostat wire going into the unit
Green to black
White to brown, The rest remain the same color inside the panel

I’m grateful for any help anyone can provide.


@leofromrio Welcome to the Wyze community!

@speadie is very helpful with the thermostat wiring and may be able to jump in here. :+1:

You should be able to upload more pics now. I noticed your trust level has changed already.


Looks like that unused blue wire at the thermostat is already connected at the control panel, it may be the C wire (typically the C wire is blue) . You could install the Wyze thermostat using the blue C wire and if it boots, you wouldn’t need the adapter.


Thank you. I will give it a try.
Is it possible to damage the thermostat or the unit by connecting the wrong wire, though?

I don’t believe so, I suspect that blue wire is the C wire, if it isn’t, it won’t power the thermostat

1 Like

That did it! Thank you!
I appreciate your help!