Red wire in B terminal on existing thermostat....

[jaxstraw11]

On my existing thermostat I have three wires (white, green,red) and a red jumper wire.

The white and green wires are connected to the corresponding W & G terminals.

The red wire though is connected to the B terminal though. 

When connecting to the Nest should I still use the same terminals ?

W to W.....G to G.....R to B

I tried doing it to the similar coded terminal yesterday ( W-W ,G-G, R-R) and all I kept coming up with was an Error 257 No Power code 

[zoeuvre]

Hi jaxstraw11, 

Uh-oh! Thanks for posting here in the Community forum and for showing interest in our Nest Thermostats. Could you send us a wiring photo of your previous thermostat and a photo of how you connected the wires to your Nest Thermostat so I can take a closer look? 

I'll look forward to your response. 

Best,

Zoe

[jaxstraw11]

I don't have a picture of how I had it attached to the Nest. I just followed the proper color coding terminals with the same color wire. 

Attached is a picture of my current thermostat and the way the wires are connected to the terminals.

[jaxstraw11]

 

[zoeuvre]

Hi there, 

Gotcha. Fortunately, your thermostat wires are compatible with our Nest Learning Thermostat 3rd generation and Nest Thermostat E should be wired to their bases as follows:

• White wire to W1
• Green wire to G
• Red wire to RH or R

Also, here's a guide for the installation and setup of a Nest Learning Thermostat and Nest Thermostat E.

Let us know if that helps.

Best,

Zoe

[jaxstraw11]

I bought the Google Nest Learning thermostat and ran the wires as explained above.

Everything works and is connected to the Wifi.

I do not have a COOL mode showing on my thermostat though so I do not see how I can run my central AC.

On former thermostat I just slid the toggle on the lower right to COOL and the thermostat controlled the AC. ,(picture attached)

This is the same thermostat that I posted how the wires were attached earlier in the thread.

[jaxstraw11]

 

[jaxstraw11]

 

[zoeuvre]

Hi there, 

Thanks for getting back to us, and I'm sorry for the delayed response. Does your Emerson thermostat have a wire connected to the Y terminal? If there's none, then there is no way for the Nest Thermostat to call for cooling since the Y1 terminal (which is the cooling terminal) is empty. Also, trace the red wire from your Emerson thermostat to your HVAC control board to see to which terminal it is connected.

Regards,

Zoe