new to NEST Community

[hdkimball]

replaced Honeywell T6 pro thermo with a Nest . everything seemed to go fine but when powered back on, a got a message No power to "C".  I have the Blue wire connected!   have tried  this several times and got the same message.

I have a very complicated HVAC system (Carrier Infinity) that nobody wants to work on and i'm thinking that the wiring is not correct at the unit's circuit board! i hate to pay a tech $150 to change a couple wires.

[CoolingWizard]

@hdkimball , can you post the picture of your old thermostat and its wiring so I can see?

AC Cooling Wizard

[hdkimball]

Thanks for your fast response! 

[hdkimball]

Thanks ,  it took me a while to attach the picture of my old thermo connections.

[hdkimball]

removed old thermo (Honeywell t6 pro) and installed NEST. get an  error message "C"  wire not connected!

it is, indeed and seated very well in the hole marked "C". it is a BLUE wire  and was connected to the "C" slot in the honeywell thermo .  have tried it several times, still has NO power to the "C" slot!

[DWB1973]

My guess is that you are not the first person to have this problem.  Have you looked through the Nest Thermostat section to see if there is an answer there?

https://www.googlenestcommunity.com/t5/Nest-Thermostats/bd-p/Thermostats

[hdkimball]

i did look through the thermo section but did not find any solutions.

thanks for responding!

[Markjosephp]

Hello everyone,

I've duplicated your thread in the main one here. You’ll receive all updates on this issue on the main thread, and we recommend updating and checking this thread when needed.

Thanks,

Mark

[CoolingWizard]

@hdkimball ,

Is it possible that the blue wire is not connected in the air handler? 

AC Cooling Wizard

[hdkimball]

if help has been suggested I seemed to have missed it.  could you please, if you have time, send a recommendation!  i should have mentioned my hvac system heats with natural gas and cools with electricity (heat pump has been disabled).

i'm new to all of this, so please bear with me - i'll appreciate any help given! 

[Markjosephp]

Hello folks,

Thanks for letting us know about the undetected common wire in your Nest Thermostat. I'd be happy to take a look at this.

@hdkimball, your C wire may not be properly grounded, so it cannot complete its circuit. To be sure of the configuration, can you share with us a photo of your Nest Thermostat's wiring? Then, gather the power readings in the Technical Info settings or in the Equipment settings, depending on your Nest Thermostat model. Also, try removing the C wire and leaving it disconnected to see if your thermostat still gets power.

Please turn off the power from your HVAC system at the breaker box first before touching the wire, and let us know how it goes.

I appreciate your input, @CoolingWizard.

Regards,
Mark

[hdkimball]

Thanks for your help!   i will be on a day trip tomorrow but Saturday i will reconnect the NEST Thermostat and take a picture to attach.

  my wire  connections with the Nest are 2 less than the Honeywell.

[CoolingWizard]

@hdkimball ,

If you have gas furnace with an AC, then you set up should be:

Rc - Red Wire, Power In 24 VAC

Y1 - Yellow Wire, Stage 1 Cooling

Y2 - Brown Wire, Stage 2 Cooling

W1 - White Wire, Stage 1 Heat

W2 - Black Wire, Stage 2 Heat

C - Blue Wire, Power Common 24VAC. This wire needs to be checked in the furnace to make sure it is connected to the C terminal on the Integrated Furnace Control board.

AC Cooling Wizard 

[hdkimball]

looks like you've solved my problem! simply put , my honeywell thermo has connections for Y2 and W2 - my Nest does not have a place to put these wires, therefore, it seems that it's not compatible with my Carrier infinity hybrid system.  THANKS for all your help!!

when i did a compatibility test it passed.  maybe it's something i missed in the test but i don't think so.  it doesn't make sense to replace an old thermo and have 2 wires (brown and black) with no connection terminals.

[CoolingWizard]

@hdkimball ,
If you do not have a Nest Learning Thermostat with Y2 or W2, you did not purchase the Nest Learning Thermostat. When I put your wires in to Google Nest Compatibility checker, it recommended the Nest Learning Thermostat. It sounds like you purchased the less expensive basic Nest Thermostat. The basic Nest Thermostat dose not support 2-stages of heat or cooling. 

AC Cooling Wizard

[hdkimball]

THANKS for your help!!    i did buy the cheapest one (through Duke Energy for $39.99). i guess i  screwed up by misinterpreting  the compatibility exercise on Duke Energy's website.

your explanation of it all makes a lot of sense!   thanks again!!

[zoeuvre]

Hi all,

@hdkimball, awesome! I'm glad to hear that everything has been sorted out. I'll consider this post as complete and will lock the thread. If you run into any more questions in the future, please feel free to create a new thread.
 

Thanks for all your help, @CoolingWizard and Mark. 

All the best,

Zoe 

[zoeuvre]

Hi there,

I want to check and see if you are still in need of any help. Please let me know, as I would be happy to assist and answer any questions you may have.

Thanks,

Zoe

[hdkimball]

i'm good, THANKS for asking!!!!!   i just had purchased the wrong NEST thermo. i received help from very capable people and i'm very pleased with this site!

again, THANKS!!

[Jenelyn_O]

Hi hdkimball,

Thanks for letting us know. Please feel free to create a new thread if you have any questions or concerns in the future, as we'll be willing to assist you.

Cheers,

Jenelyn