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I just installed a new "Nest Thermostat" - says c wire has no power

Delvalle7
Community Member

I see a lot of people have this issue-- is it a flaw with the google nest?  I removed an old thermostat that was functioning properly but wanted to upgrade.

I do have a C wire-- it is blue.  It is connected at the thermostat and on the motherboard of the AC/Heat unit

I did "restrip" the wire to make sure that the wire was fresh and making good contact.

The Nest Google I have has a mirror like face.  It does not say learning or anything else. 

Google Nest Thermostat "Snow"

I don't see a model number per se-- I do see a code which *may* indicate model?  M: G4CVZ with a MFG date of 09/2023

It is supposed to ger very cold tonight.  Can I run it temporarily without the C wire?  even if I can-- what do I need to do to fix the google Nest Thermostat so that it functions properly?

39061J

1 REPLY 1

aperezdeleon
Community Specialist
Community Specialist

Hi there Delvalle7.

 

Thank you for reaching out to our community.

 

Having your thermostat not recognize the C wire properly can be frustrating because it prevents proper installation. However, don't worry. I'm here to help.

My first recommendation is to rule out any issues with the C wire. Make sure the connected wire can provide a steady power signal.

 

If you're still in the setup phase, remove the batteries from the thermostat for 5 minutes and then try the setup again. When setting up, select the correct heating/cooling system you have. Choosing the wrong system type can prevent the Nest thermostat from detecting the C wire.

 

While you can make the Nest thermostat run without the C wire, it's not recommended. If your system requires the C wire for consistent power, your thermostat might lose battery power unexpectedly, especially during long heating or cooling cycles.

 

As a last recommendation, there's a possibility that the C wire in your unit isn't properly grounded, which could cause this error message. If that's your case and you're looking for long-term solutions, contacting a technician might be helpful.

 

Please keep me posted.

Regards,
Angel