topic Re: Converting a Vivint CT100 to a Nest Learning Thermostat Gen 3 in Nest Thermostats

Converting a Vivint CT100 to a Nest Learning Thermostat Gen 3

drshawnse — Mon, 04 Dec 2023 14:20:26 GMT

Hello-

I'm converting a dual zone residence (forced air natural gas furnace downstairs and electric heat pump upstairs) to the Nest Learning Thermostats Gen 3. After installing the thermostat for the downstairs (works great!) the upstairs thermostat is giving me fits. The upstairs thermostat that the Gen 3 is replacing is a Vivint CT100 with the following 7 wire configuration:

C - Blue
B - none
O - Orange
W - none
W2 - White
Y - Yellow
Y2 - Black
RH - Red (with jumper to RC)
G - Green
A - none

CT100 Wiring

Here is the wiring to the new Nest base:

When I connect the thermostat to the base, it gets no power. I can set up the thermostat while connected to USB and the unit charges. When I connect to the base, the thermostat goes offline and get the following in the Nest app:

"Unknown: There's a problem with your thermostat's wiring."

Nest App Screenshot

Any suggestions on wiring for the base would be much appreciated. After discussions with Google product support, I have moved the RH to RC, but no change in power status.

Thank you!

Re: Converting a Vivint CT100 to a Nest Learning Thermostat Gen 3

zoeuvre — Thu, 07 Dec 2023 15:55:49 GMT

Hi drshawnse,

Oh no! I'm sorry to hear that your recently installed Nest Thermostat is giving you no power error. What is the exact power error message that your thermostat shows? Also, follow these:

Reset the breakers.
Make sure that the thermostat base is properly installed on the wall.
Make sure that the wires connected from the thermostat base to the HVAC control board are firmly connected with no loosed or exposed wires.
Gather the power readouts of Battery, VOC, VIN, and lIN under Settings > Technical Info > Power.

Keep us posted. We're happy to help.

Best,

Zoe

Re: Converting a Vivint CT100 to a Nest Learning Thermostat Gen 3

drshawnse — Fri, 08 Dec 2023 01:03:57 GMT

Thanks for the reply. The display shows a single solid orange light when plugged into the base.

Re: Converting a Vivint CT100 to a Nest Learning Thermostat Gen 3

Jenelyn_O — Tue, 12 Dec 2023 20:59:02 GMT

Hi there drshawnse,

Chiming in — it looks like you also have an incorrect humidity readout. When did you purchase your thermostat? I'd like to take a closer look at it. Please check your thermostats Signal Strength by going to Settings > Technical Info > Network.

Try the steps in this guide:

Remove the thermostat display from its base for about 5 seconds.
Reattach the display.
Wait for 10 seconds.

Let me know how it goes.

I appreciate your help, Zoe.

Regards,

Jenelyn