Adding AC to an existing Nest themostat

[webba]

I have an existing Nest thermostat (software 1.5.38/3.1 and model Backplate-5.3) that I use to heat my upstairs bedroom.  It works great - no issues.  However, I also have another older thermostat in the same room that controls my central AC for the entire house.  I would like to know if I can get rid of the older AC thermostat and have my Nest thermostat control both the heat and the AC.  

Here is the wiring configuration for the wiring of my Nest thermostat that currently controls my heat:

Here is the wiring configuration for the old thermostat that currently controls my AC:

Can I consolidate all the wires into my Nest thermostat so that it controls both my heat and my AC?

Thank you in advance for any help you can provide.

[Patrick_Caezza]

Since you have the Nest Learning Thermostat you can.

Don't change any of the heating wirings.

Try this for the AC wiring.

Red - RH to Rc

White - Y to Y1

Green - G to G

Good chance you will need to add a C wire and it has to come from the cooling side. If there is no wires that you can use, the Nest Power Connector will be an option

[aatienza]

Hey there,

@Patrick_Caezza, thanks for the help!

@webba, still need help with your thermostat? Let us know, we're glad to assist.

Thanks,

Archie

[aatienza]

Hey webba,

I just wanted to follow up and see if you're still in need of help. Please let us know as we would be happy to answer any questions you may have. 

Thanks,

Archie

[webba]

I think I'm all set.  I haven't had a chance to run the thermostat wire yet but I have a good idea of what I need to do.  Thanks for checking in.

[aatienza]

Hey webba,

That's good to hear! Since this has been resolved, I'll mark this thread as complete and will lock the thread in 24 hours.

Feel free to start a new thread if you need assistance with your thermostat. 

Thanks,

Archie