Have both an O and a B wire; not sure how to connect Nest Learning Thermostat

[Duane1]

Am in Arizona and have a combined AC & Heating unit on the roof (possibly a heat pump). Replacing a Trane thermostat. Wires were connected as follows: Red wire to R; Yellow Wire to Y; Green wire to G; White wire to O; Blue wire to B. What is the proper connections to the Nest?

[Patrick_Caezza]

Trane uses the B terminal for the C wire.

Just match the label and connect the blue wire to the C terminal, and you should be all set

[aatienza]

Hey Duane1,

Checking in — we hope you've got the answer you're looking for. Let us know if you have more questions in mind.
 

I appreciate the help, Patrick_Caezza.

Thanks,

Archie

[EmersonB]

Hi everyone,

@Duane1 I just wanted to follow up and see if you still need any help? Let me know if you have any additional questions from here.

Thanks for your help, @Patrick_Caezza and @archie.

Regards,
Emerson

[EmersonB]

Hello Duane1,

We haven’t heard any updates from you. I’ll go ahead and lock this thread in 24 hours. If you're still in need of assistance, feel free to start a new thread and we'll be happy to help.

Best,
Emerson