What does “vin” mean?

[Scarlettsjt]

So my furnace is short cycling recently and never reaches the set temp. 
After talking with the customer service, and furnace repair guy, the issue is probably with Nest( 3rd generation learning), or the battery if more specific. 
One problem is that the Vin is always 30+v, never between 6-7 when the system is running. I don’t have a C wire. Anyone knows what does this mean? 

Battery is below 3.8 most of the time. Other readings are normal. 

[Houptee]

Watch this video

https://youtu.be/GHkfnRp6Tj8

[Scarlettsjt]

So, I installed this thing called “Nest Power Connector” —a alternative to Common C—and solved my problem. It’s day and night difference than before. But I can still hear the blower turning on and off  and then the furnace completely shut off for a while before  it kicks on again and reaches the set temp. Should I worry? should a furnace running nonstop before reach the temp? 

[Markjosephp]

Hello there,

Thanks for assisting, Edward.

@Scarlettsjt, I know it has been a while, but I wanted to ensure that everything was covered here. How's it going? Are you still experiencing the same issue? Also, could you please check your thermostat's power readouts? You can find this under the Technical Info on your actual thermostat's settings. 

Regards,

Mark

[Markjosephp]

Hi Scarlettsjt,

It's me again. Checking back in — how's it going? Still need our help?

Thanks,

Mark

[Markjosephp]

Hello Scarlettsjt,

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.

Regards,

Mark

[EdwardT]

Hi folks,

@Houptee, thanks for the help!

@Scarlettsjt, how's it going with your Nest Thermostat? Still need our help?

Thanks,

Edward