Thermostat reading wrong temperature

[Dtreg]

I have a 2.12 version Nest.  It has worked no problem for years. Today the display is reading 9 degrees higher that actual room temperature and when I remove display base is warm.  I read some threads that this has been an issue..

Also at same time fan is running and won't stop even when I turn system off on display. 

[Dtreg]

Want to know if my theory might be right after reading posts for both the hot base and fan issue...  since the base remains warm after the display is removed and fan stays on and only cools when I turn the breaker off and then reheats when it's back on with the display off..... my theory is that there is a short in the Nest base that is keeping the fan on and is causing the warmth on the base... logical?  If so have to replace base and thermostadt...

[zoeuvre]

Hi Dtreg, 

Yikes! I'm sorry to hear that your thermostat is reading 9 degrees higher than your actual room temperature and your fan is running and won't stop even when you turn your system off on display. Let's see what's going on. A few questions: 

1. Are you located in North America or Europe?
2. What type of Nest Thermostat do you have?
3. When was the thermostat installed?
4. Where did you install your thermostat? In a room and on a wall or stand? 
5. Do you have other active Nest Thermostats? If yes, do they show the same issue?
6. Have you tried any troubleshooting steps? If yes, would you mind listing them?

If you have the Nest Learning Thermostat or Nest Thermostat E, go to Settings> Technical Info > Network and check for Signal strength value. The signal strength has a maximum value of 100. A signal strength of 75 is considered strong, while a value of 36 or lower is considered weak.

Keep us posted. We're happy to help.

Best,

Zoe

[Dtreg]

We are in North Carolina... it is a Model 2.12 learning thermostat.  It was installed before we bought the home so it's at least 3 years old.  We never had any issues with it in past heating or cooling seasons.  It actually worked fine heating at the beginning of this fall, then all of a sudden we had the issues.  The WIFI connection is strong.  We have a total of 4 Nest thermostats, all the same model... no issues with them. The issue is definetly with the base... if I pull the display after putting the Nest in "off" mode the fan still runs AND the base stays warm.  Only way base cools off and fan stops is to turn the heating/cooling system breaker off.  Soon the base cools off.... if I turn the breaker back on, with the display still detached, the fan goes on immediately and the base starts to warm up.  So my theory is a short in the base...

I have ordered a new Nest learning thermostat from my utility company (with a energy saving rebate).  When I get it I will replace.  Hopefully that does it. 

[Dtreg]

Ok got the new 3rd gen Nest.  Disconnected old base and verified fan wouldn't work w/ all thermostat wires disconnected, eliminating possibility of bad fan relay.  Installed new thermostat, connected to WIFI and turned system back on, with thermostat in off mode.  Fan stayed off (yea!).  Reset everything and heating as we speak with no problems.  Seems like my theory of a short in base was correct.  Took base apart and no visable issues on circuit board... keeping fingers crossed that problem solved.🤞

[zoeuvre]

Hi there, 

Awesome! I'm glad that you managed to resolve this issue, and I appreciate your sharing the steps you took to resolve this case. I'll keep this thread open to see if this resolution will no longer revert back to the issue.

Thanks,

Zoe

[jonfetx]

So the steps he took to resolve his issue was — to get a new one?  Wow.
I've read a bunch of these posts out there with  issues of the thermostat not reading correct temperature. I have the same problem. Isn't that like the MAIN goal of a thermostat... to first be able to sense the exact ambient temperature?  Wish someone at Nest would figure out how to fix. Seems like a ton of people have the same problem. Whether it be 2º like mine or 10º like others. Very disappointed. This is an expensive piece of tech for it not to be able to accurately do it it's number one job.

JonFet

[Dtreg]

While some posts I saw, especially those on the lower temperature differential area could be caused by a combination of the way the nest measures room temp and where the thermostat Is located (warm wall), mine was clearly a failed base.  The thermostat was installed years ago and the 10 degree difference occurred all at once combined with the fan not shutting off.  The base was warm and stayed warm even with the display off.  To me clearly a short causing both... I agree that with number of people seeing similar issues Nest would address, especially with the new 3rd generation units... we will see

[bcgoods]

I also have a Nest Learning 2.12 model that all of the sudden is registering temps 9-10 degrees above actual room temperature.  This is really disappointing since these this is as you say an expensive piece of equipment.  Can you order a new base if this is causing the problem?

[Dtreg]

I could not find a way to buy only a base since I was out of warranty I had to buy a whole new Thermostadt.  Check with your utility some offer special pricing or rebates on new nest units.

[zoeuvre]

Hi folks,

It's me again—I'm sorry for the delayed response. I want to check if there might be anything else you needed on this or if you had any other questions. If there's more you need, just let us know.

Regards,

Zoe