E74 code no power to rh wire

[LARVA]

Hello, 

I self-installed my 3rd generation learning nest thermostat. It was working great for 20 minutes then told me there was no power coming from the Rh (red wire). Everything was working for the last thermostat. I tried to reset everything, take the cord out and turned the power off for 20 minutes. After that, it worked for five minutes and then had the same message.

I've triple checked the wires, the wire is clean, it's fully inserted, and I've cover the basics. Any other ideas?

Thanks!

[Patrick_Caezza]

@LARVA 

Post a picture of the original thermostat wiring and one of how the Nest is wired

[Kmorales]

Did you get this issue resolved? I am having the same issue

[Poppyjunie]

Same issue ! Is there a number to call to help?

[LARVA]

Hi, everyone- I found a link you can request help, but I can't post it here. I ended up DMing google nest on twitter and they shared it with me.

I tried to walkthru with google 3-4 times, but we were never able to make it work. I ended up hiring someone google recommended to come and hopefully fix the problem tomorrow.

The simple solutions google tried was removing the c cord since the Rh cord gives power. I did not understand why this would work. but it did fix that problem. However, this caused the device not to work with my ac. 

I would encrouage you to fill out the form and someone will likely call you in a minute or two. 

[Jenelyn_O]

Hi everyone,

Thanks for posting in the Google Nest Community forum. E74 code will show if your Nest Thermostat doesn't detect power to a wire, or it can't detect the wires in your thermostat. Please try to troubleshoot your systems power and wiring by following this link. Please let us know how it goes. 

I appreciate your help, @Patrick_Caezza and @LARVA. 

Best,

Jenelyn

[EmersonB]

Hello everyone,

We wanted to follow up and see if you are still in need of any help. Please let us know if you are still having any concerns or questions from here, as we would be happy to take a closer look and assist you further.

Thanks for answering, Patrick_Caezza and Jenelyn.

Regards,
Emerson

[Dan_A]

Hello again,

We haven't heard from you in a while so we'll be locking this thread if there is no update within 24 hours. If you need assistance or want to discuss topics, feel free to start a new thread.
 

Cheers,

Dan

[Agymteach]

I need help with this same problem. My Nest has worked fine for years and just started getting this same error about the Rh wire not getting power. It is intermittently going off and on. I have pulled the wires out , trimmed them and reinserted but this has not fixed anything. Please help. I’m hot!🥵

[Mcaldwell]

Same problem here. Worked great for years and now says no power from Rh wire. Makes no sense. 

[kjl0115]

Am having same issue.  My furnace fan is running but no A/C.  E74 error on Nest.  Can't get someone here to look at it for 10 days.  What can I do myself?

[Jenelyn_O]

Hi there,

@Agymteach,@Mcaldwell, and @kjl0115. Thanks for reaching out. Could you please provide the power readouts of your Nest Thermostats? 

You can follow these steps:

1. Go to your Nest Learning Thermostat Quick View Menu.
2. Go to Settings.
3. Turn the ring until you find the word Technical Info.
4. Choose Power.

Best,

Jenelyn

[kjl0115]

On Power:   Battery 3.704

VOC 0.07V

Vin 0.07V

lin

[Jenelyn_O]

Hi kjl0115,

Thanks for that information. Try to remove and reinsert your power wire and ensure that the tab beside the terminal is pressed down. Make sure to turn the breaker off before touching the wires. You can also try to move the red wire from RH to RC terminal to isolate it further. 

Let me know how it goes.

Regards,

Jenelyn

[kjl0115]

Do you know which circuit breaker I turn off to do this?  I see the one for the A/C.  Is there another one that powers the Nest?

[Jenelyn_O]

Hey kjl0115,

If your Nest Thermostat also controls your furnace or heating system, turn it off as well. You can check out this link for additional reference on how you'll troubleshoot this power issue.

Best,

Jenelyn

[Jenelyn_O]

Hi there,

Checking if you still need help. Please let me know, as I'll be willing to assist you further. 

Thanks,

Jenelyn

[Jenelyn_O]

Hi folks,

Just one final check in here since activity has slowed down. We'll be locking the thread in the next 24 hours, but if you still need help, I would be happy to keep it open. If there's more we can do, just let me know. 

Regards,

Jenelyn