Nest Thermostat 3rd G

[Moman2]

is my system compatible with Nest Thermostat.   As you can see, there are 2 sets of wires.  A set going to the left (labeled as W,RH,B,C).   Another set going down (labeled as C,G,O,Y).  By looking at the wires of both OLD and NEW system,  I found out that the old system wiring has a seperate "O" and a seperate "B".   While the new NEST system has only one wire called "OB".  My question is which one from the old system goes to "OB"?

[Patrick_Caezza]

@Moman2 

Post a picture of the original thermostat's wiring here.

If the camera icon isn't present yet, you can use the Igmur.com Upload site and post the link it provides here.

[Moman2]

Thank you, Patrick.   I was able to  add the info you asked.  Please check and let me know 

[Patrick_Caezza]

@Moman2 

Can you post a picture clearly showing the thermostat's terminal blocks with labels showing? You have the RC terminal labeled as C.

If possible, can you take and post a picture of the terminal block on the control board in the air handler/furnace?

[Moman2]

@Patrick_Caezza, Here is another picture with labeled letters beside it

[Moman2]

@Patrick_Caezza, I replied to your question in the previous relpy.  Can you check and let me know

[Moman2]

@Patrick_Caezza,  As you can see, from the last picture I posted, one set of wires going to the left (labeled as W,RH,B,RC).   Another set going down (labeled as C,G,O,Y).  By looking at the wires of both OLD and NEW system,  I found out that the old system wiring has a seperate "O" and a seperate "B".   While the new NEST system has only one wire called "OB".  My question is which one from the old system goes to "OB"?

[Patrick_Caezza]

@Moman2 

Apologies for taking so long. I got swamped with work.

The O and B terminals might mean it's not compatible with any Nest thermostat.

Take a look at the air handler and see where those two wires are connected.