Nest thermostat wiring help

[Drholland]

I need some help. I’m installing the nest thermostat and it’s telling me that c wire has no power. So I did some digging because on my Honeywell, the c wire was brown, but within the bundle I found a blue wire that went no where. Now I haven’t gone into my attic to confirm (I know I need to) but both the blue and the brown are reading 24volts but I’m still getting the error that there is no power when either is inserted into the c port. Why? 

[Markjosephp]

Hello Drholland,

I'm sorry to hear that you're having an issue with your Nest thermostat installation. I'd be happy to take a look into this for you.

A few questions: which Nest thermostat are you installing? Here's a reference to help you figure out which one you have. Do you mind me asking for a picture of your previous thermostat wiring setup? Also, what's the message code or wire report that you're getting?

Please take a look at this article and let us know if you need more help.

Best regards,

Mark

[Drholland]

Hey there, it’s the nest learning thermostat.  I have two units so I tried it downstairs and it did the same thing. Again, I read the voltage and was getting over 24volts but still when I put the thermostat on the base it tells me that C has no power, which it does. I have a Honeywell thermostat without a heat pump with red having a jumper from r to rc, white in W, yellow in y, green in g and brown in c. Once I put those in their corresponding spots on the learning thermostat and I turn power on i get e74 error with no power to c wire. Again.. i read the voltage between the red and brown wire and have 24 volts so I’m not sure if it’s a thermostat issue and I need a new one or what 

[Markjosephp]

Hi there,

Thanks for letting me know, and I appreciate that you've tried finding a fix. Let's find out more about what happened.

It appears that the common wire may not be properly grounded, so the system uses power sharing but doesn’t get enough energy. Going over the steps here might help:

1. Please check the power status on battery level, Voc, Vin, and Lin under technical info.
2. Then, try installing your Nest thermostat without the C wire, and then install the rest of the wire setup.
3. Restart your thermostat; tap and hold the thermostat screen for 10 seconds until it shuts down to refresh.

Please note: turn off the power from the HVAC at your breaker before touching the wires.

Let me know how it goes.

Best regards,

Mark

[Markjosephp]

Hi Drholland,

I'm checking back in. Were you able to do the steps above? I'd be glad to hear from you — I'd like to make sure everything is working.

Best regards,

Mark

[Drholland]

I’m out of town but will check that when I get back! Thank you so much I will let you know right away 

[Markjosephp]

Hey there,

Thanks for getting back to me and letting me know.

No worries! You can continue the steps whenever you're available. Also, please keep us updated on how things progress, and I'd love to know what the outcome is.

Best regards,

Mark

[Markjosephp]

Hi Drholland

It's me again. I'm checking back in — how's it going? Still need our help? Let us know so we can assist you right away.

Best regards,

Mark

[EmersonB]

Hi folks,

@Drholland just one quick 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.

I appreciate the help, Mark.

Regards,
Emerson

[Drholland]

I am going to give it a try today. But question, why would this same thing be happening on two separate units? 

[EmersonB]

Hey folks,

@Drholland thanks for reaching out again. We would recommend you to check the other end of those blue and brown wires if they are properly connected to their respective terminals and take note of their labels for your reference. You may see it from your control board.

We'll wait for your update.

Best,
Emerson

[EmersonB]

Hi Drholland,

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

Regards,
Emerson

[Jake]

Hey there,

I wanted to check in, and let you know that I will be locking the thread in 24 hours.

Best regards,

Jake