cancel
Showing results for 
Search instead for 
Did you mean: 
Replies are disabled for this topic. Start a new one or visit our Help Center.

Wiring for nest thermostat

Mikering
Community Member

image.jpgThis is my current configuration but when I try to connect to the learning thermostat model 02A I get no power detected from RH/RC  with it showing all other connections are good. Though when connected to the current thermostats unused black wire it will display those as power but then the C wire displays as failed. I’m at a loss of what the issue is, I've been able to wire it with no issues in past places I’ve lived it’s just here that’s the issue. I’ve compared where the different components in the wiring diagrams say they should go while keeping the current wire colors matching… any help would be greatly appreciated.

Thanks in advance!

14 REPLIES 14

CoolingWizard
Platinum Product Expert
Platinum Product Expert

You have no power detected because you need a C wire.  I notice an Orange and a black  conductor not being used, so it possible to get C signal to the thermostat.  You system has 2-stages of heat they are W1 and W2. You will will need to use say the black wire and connect it to the C terminal on the furnace control control board.  

The AC Cooling Wizard

NestPro, Google Pro, Mechanical Engineer and HVAC service company owner.
If my answer solved your problem, click Recommend this Answer below, and If it helped you, please give a Kudo.

Thank you I’ll test using the black wire instead of the brown as the C, would the brown go into the W1 and the white to w2 then? The wiring is for a heat pump if that changes things.

CoolingWizard
Platinum Product Expert
Platinum Product Expert

Being that what you have is a heat pump thing that makes a lot of difference. That means the blue wire controls the O/B, and the white wire is AUXILIARY heat. 

The AC Cooling Wizard

NestPro, Google Pro, Mechanical Engineer and HVAC service company owner.
If my answer solved your problem, click Recommend this Answer below, and If it helped you, please give a Kudo.

Hello folks,

 

I'm dropping by to see how I can help.

 

I appreciate your expertise here, @CoolingWizard.

 

@Mikering, I wanted to see if you still needed help. How's it going with the installation? Have you had a chance to make the wiring changes suggested by CoolingWizard? Please let us know if you have any other questions or concerns.

 

Regards,

Mark

Hi Mikering,

 

I know it has been a while, but I wanted to ensure that everything is covered here. How's your thermostat now? Still need our help? Please let us know so we can assist you right away.

 

Thanks,

Mark

aatienza
Community Specialist
Community Specialist

Hey there,

 

Just checking in to make sure that you've seen our responses. Please let me know if you have other questions or concerns as I will be locking this in 24 hours if I won't hear back from you again. Feel free to start a new thread and we'll be happy to help.

 

I appreciate the help, Mark.
 

Thanks,

Archie

My apologies I was not receiving update notifications, I still haven’t gotten the wiring sorted out. 

I’m not understanding how the red isn’t giving power though it does when I’ve tied 2 other thermostats? I’m also not quite sure where I would put each wire. Currently it’s y1 yellow, g green, ob blue, rc red, aux white, c brown

Jenelyn_O
Community Specialist
Community Specialist

Hi there,

 

I saw your post and wanted to chime in — I'm sorry for the delay. I just want to follow up if you're still encountering the issue. Please let me know as I'll be willing to assist you from here. 


Thank for your help @CoolingWizard, @Markjosephp, and @aatienza.

 

Best,

Jenelyn

Markjosephp
Community Specialist
Community Specialist

Hello Mikering,

 

I know it has been a while, but I wanted to ensure that everything is covered here. 

Going over these steps might help: 

 

  1. Please turn off the power of your HVAC system at the breaker box before touching the wire. 
  2. Try removing the C wire and leaving it disconnected. 
  3. Ensure that the other wires are still properly connected and the tabs are pushed down. 
  4. Press and hold the thermostat screen for 10 seconds until it shuts down to reboot.

 

Let me know if that helps.

 

Regards,

Mark

Hi Mikering,

 

It has been a few days since your last reply, and we're going to lock the thread within 24 hours. If you have any questions, please feel free to create a new post.

Thanks,

Mark

CoolingWizard
Platinum Product Expert
Platinum Product Expert

Mike, you should use a volt on meter and check AC voltage between the red wire and the brown wire and tested between the red wire and the black wire and see if you get any voltage reported

Ken, the AC Cooling Wizard

NestPro, Google Pro, Mechanical Engineer and HVAC service company owner.
If my answer solved your problem, click Recommend this Answer below, and If it helped you, please give a Kudo.

Hello there,

 

Thanks for the continued support, Ken.

 

@Mikering, I'm checking back in to see if you were able to try testing your thermostat's wires. How's it going? Could you please tell us their readouts?

 

Regards,

Mark

Hello Mikering,

 

I wanted to see if you still needed help. Please let us know if you have any other questions or concerns.

Thanks,

Mark

Hey folks,


It looks like we haven't heard back from the OP, so I'm going to lock the thread within 24 hours. If you have any further questions or concerns, feel free to create a new thread.


Thanks,

Mark