Nest Thermostat Jamming

[Mich1]

As of Fall 2022, I've been having an issue where my Nest (learning thermostat), after it's been running heat for a while, will sort of jam up.  It will appear as if it is in the process of heating, but the furnace is off and the temperature is actively dropping.  The only solution I've been able to figure out is to go and turn the furnace master switch off and then on again.  This essentially reboots the furnace and the Nest.  

This is not a sustainable solution and I'm curious if others have encountered the same issue?  If so, what is the fix?  I don't want to have to buy another thermostat.  (Mine is currently out of warranty, FYI).

[Divineearth7]

I’ve been having this same issue for the past 3 days. I also rebooted and it works normal. I hope someone can figure this out. 

[Mich1]

Rebooted your furnace or your Nest?

[Divineearth7]

Both 

[jslaff]

Same here. Noticed it takes a while for the heat to come on when it's called for in the morning. I'll try to restart the Nest once the house is warmer. If we're all having similar problems since Friday, I wonder if Nest pushed some update to the unit that had unintended consequences.

[Markjosephp]

Hello folks,

I'm sorry for the trouble this may have caused everyone, and I appreciate the steps you've all taken. Let's see what's going on.

To isolate: could you please tell us which Nest Thermostat models you have? Does it have a C-wire or a Nest Power Connector? Also, please check the power readouts on the "Equipment" settings for the Nest Thermostat 2020 model and "Technical Info" for the Nest Learning Thermostat and Nest Thermostat E versions.

I'll look forward to your responses.

Regards,

Mark

[Divineearth7]

I’ve also noticed that my heat on stays on if I set it to 75° or higher

[Mich1]

I have a Nest Learning Thermostat (Model 3.7) with C wire.

Battery: 3.871 V

Voc: 37.41 V

Vin: 37.41 V

lin: 200 mA (c)

[Mich1]

Hi Mark,

Are you able to further troubleshoot this issue now that we've shared the diagnostic info you requested?

[Markjosephp]

Hello there,

I'm sorry for the late reply, and thanks for the details.

@jslaff, you might have had an Eco Temperature or Home and Away Assist issue. To better assist you with this, I'd suggest that you please create a new post with the details you've shared to avoid confusion on this thread about the heating that deactivates or won't turn on.

Thanks for checking the power readouts, @Mich1 and @Divineearth7. I'd love to know more about this.

• Do you see any timers on the screen when calling for heat?
• Does the issue occur randomly and intermittently?
• Is cooling activated and working as expected?
• Were there any recent repairs made to your HVAC system?
• Do you have any other thermostats or a Nest thermostat? Does it show the same issue?
• Check the air filter. A clog in the air filter can limit how much air flows.

Let me know how it goes.

Regards,

Mark

[Mich1]

The only pattern I've been able to establish with this issue is that it happens after the heat has been running for a while.  We have old/drafty windows that lead to significant heat loss, and so on especially cold nights the heat runs frequently.  This issue happens predominantly after midnight.

No recent repairs to HVAC equipment, no other thermostats, filter was changed in the last few months.

[Divineearth7]

This is still an ongoing issue. I’ve had no major repairs and also the filter has been changed recently. The solution I have is to turn the thermostat down really low then high again and it seems to run for a little while then shut off. When I go to the nest app it shows the heat is on even when the furnace is off. I really hope this issue is resolved soon. Also it is no longer learning my heating pattern as well.

[jslaff]

The thermostat problem came back, randomly. I reset the Nest back to factory default settings and reprogrammed the schedules. That seems to have fixed it. 

[Markjosephp]

Hello folks,

I'm sorry for the late reply, and I wanted to ensure everything was covered here.

@Mich1 and @Divineearth7, thanks for the details. I know it's been awhile, but how's it going with your Nest Thermostats? Are you still experiencing the same issue? Let us know if you need more help.

@jslaff, thanks for updating us on what you've done to have your concern rectified. If you're still in need of assistance, feel free to create a new thread.

Regards,
Mark

[Mich1]

For me, nothing has been addressed.  I would love to just get my money back and buy a different smart thermostat at this point.  Is that something you can help with?

[Divineearth7]

I have the Nest E model with the C wire. Power is R 

[Divineearth7]

Battery: 3.894

voc: 37.63v

vin: 36.17 v 

lin: 40mA (i)

[jslaff]

3rd gen Nest Learning thermostat, dedicated C-wire, battery at 3.90 volts. It works perfectly after I rebooted it (didn't reboot the furnace). Also, I changed the fan schedule from 15 minutes an hour to continuous.

[jslaff]

Here's another point. It was sensing no one was home early in the morning when the schedule turned on the heat, and reverted to Eco. I turned that off, and the heat came on and stayed on correctly. Eco when no one's home is the main reason I purchased a Nest. If that's broken, what's the point of having it?

[Mich1]

I think you and I are having different issues.  My Nest isn't reverting to Eco mode, it's just staying stuck in the heating mode even though the furnace is not running.  When I look at the energy history on the app it shows a solid block of orange from like 1am to 5am ... and the furnace was off that entire time.