Learning Thermostat Stopped Working

[TJS54]

I have two learning thermostats 3d generation.  In February both stopped working after being installed the previous April and operating without a problem.  I went through diagnostics with the google helpline but nothing worked.   I scheduled a company referred by google to service the units.  Before the service date, the thermostats started working again on their own.  They both worked fine until mid April when one thermostat stopped working after my AC received its annual service,  The thermostat, once charged using usb, works fine, is connected to the internet and can be controlled by the app.  But it only last a few hours.  It is then has a black screen.  The VIN reading is low (4 to 5).  The google helpline says I need a nest power connector (since there is no C wire).  Why is one thermostat working fine and the other is not?  Will the thermostat NOT working be OK after the connector is installed or was the internal battery damaged?  

[zoeuvre]

Hi TJS54, 

Thanks for reaching out to us, and I'm sorry to hear about the situation. Let me take a look at this for you.

Google Nest thermostats require a C-wire or a Nest Power Connector to provide steady power and maintain current flow, if power problems occur. What is the exact error message your Nest Learning Thermostat shows? Also, please help us with your Nest Learning Thermostat's complete power reading?

1. To open the Quick View menu, press the thermostat’s ring.
2. Choose Settings.
3. Turn the ring to highlight Technical Info then press the ring to select it.
4. Select Power. 
   • Battery
   • VOC
   • VIN 
   • IIN

I'll look forward to your response.

Best, 

Zoe

[Dan_A]

Hey there,

I wanted to follow up and see if you still need 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,

Dan

[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