enter image description hereMy current thermostat is wired as follows and the wires are from my Separate heater and separate AC air handler:

W - From my heat R - From my heat

Rc - From my AC Handler Y - From the compressor G - From the AC Handler

Do I need to add a wire for the C connection but am unsure whether I need to do that how and where to connect it. Our can I do something else with the G wire? I have attached a pi of my current schematic, can anyone please help?


In the picture below you can note that the connection labeled with a 7 in a triangle is the "C" of your fan controller. As per your added note to the diagram this is also connected to your A/C unit so there is a common "C" between your A/C and the fan controller. This same place is where you want to connect a spare wire to run for the "C" terminal on your thermostat.

enter image description here

  • Oh, the reason I have posted this is because I want to install a Honeywell 9000 Wifi thermostat and it needs a "C" wire. I had seen a few Youtube videos about alternate ways to add a "C" wire so I didn't know if I could just connect to the "C" at the 7 (which is on a wire nut above my AC air handler). – Dave S Jan 19 at 15:34
  • @DaveS - You ask again where to connect for the thermostat. Yet I already said where in my answer. – Michael Karas Jan 24 at 1:47

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Not the answer you're looking for? Browse other questions tagged or ask your own question.