Nest randomly changes temp to 50 or 90 degrees

[Divamac]

This is my second Nest with the same issue. First was replaced under warranty but the same problem persists. It’s a 3rd Gen thermostat. 

unit was professionally installed 3 years ago with a new HVAC system. 

The thermostat is usually set to Eco mode, but it will randomly change temperature to 50 or 90 degrees on its own. I’ve reset, powered off, turned off every automated feature (no schedule, no home/away, no learning) and I now have the thermostat covered with a box so it’s motion sensor is blocked. It’s not a security/access issue. Hours have been spent on the phone troubleshooting. Again, this is the second unit with the same issue. 

I’m ready to replace it with something else. I see this issue posted elsewhere with no fixes offered. Has anyone found a solution?

[Shammy]

Me too. Just had AC come on — thermostat was set to 55 degrees! Neither me or my husband did THAT! 

[Shammy]

And this evening we suddenly realized the heat was set to 80 degrees! That’s nuts. Either Google has a bug or their system has been hacked to hack mine!

[AmberJack]

Omg, I have the same issue! I constantly have to check to make sure it's not changed to some crazy temperature. 

Has anyone found a fix?

[Scott25929]

Ugh me too.  I get home from work and the house is set to 50.  So annoying

[AmberJack]

I constantly have to monitor my thermostat throughout the day via phone. 

Do you have that option? 

[Divamac]

Yes. I work from home, so as soon as I hear the unit come on, I turn it off. 

I keep the unit on the OFF setting now. It turns itself in to 90 degrees randomly. I’m going to have to buy a different (non-Nest) unit. This is too frustrating. 

[Amacrae]

I have the same issue heating set to 14c at night and scheduled to 19c at 6am, however at 3am the heating temperature changes itself to 19c.

Any help would be greatly appreciated as at the moment I have to switch heat off and then get up at 6am to set back to heat.

Auto learning is off.

[MoneyOverMen]

I have something very similar. It changes the thermostat to 68 degrees in the winter. Wakes me up every single time because it gets so hot! I turn it down every single day. It's cost me a lot of money with this thermostat! So **bleep** hot! It even overrides the settings to bring it up to 68 degrees.

[AmberJack]

Please EVERYBODY post a fix for this if/when you find one. 

What are we going to do? Mine is still on the fritz, changes temperature constantly and goes from heat to eco, ac to eco and even changes the set temp in eco. I don't want to buy a new thermostat 😪

[Divamac]

I still don’t have a fix. Even covered with a box and powered off, with all automations turned off, it turns itself on to 90 degrees or to 55 degrees.  I don’t see that the manufacturer cares at all about it. 

[MoneyOverMen]

Ok...I was bound and determined to find something. If your temps are consistent, it has to be a setting. So what I found was, in Settings, and you have the chart that shows all the temps your thermostat was going to...you can change those temperatures. Just go into that graph one by one and change it to what you want. Somewhere along the line, they must have come preset with funky temperature settings. There has to be a better way than to do it manually like this, but that solved my problem. You can also do that on the thermostat. Go into Settings and change it. These temps were coming from somewhere. And I found them there in Settings. If you need more help, let me know.  Signed...Finally sleeping without checking my thermostat all night!!!

[Divamac]

Scheduling is turned off on my unit. All automations and learning settings are off. It happens randomly. I’ve been troubleshooting this for years without a solution. 

[Divamac]

 

[Fera]

I am trying to find location of this graph can you please give me a little more detail on where you found it. I only see active history and no graph there thank you Stan 

[Divamac]

This is the Schedule you access from the main app screen. 

[MoneyOverMen]

Both the thermostat and the phone app have a way to change these settings. You must go into settings. That's where the schedule is on both. 

[Divamac]

 

[MoneyOverMen]

If you go into Schedule on your phone, it will bring up that 'graph'. Go ahead and pick a temperature that is too high or too low. If you touch one of them, you can change the temperature from there. You have to have small fingers and move slowly. I haven't figured out a way to make a change across the board but there has to be a way. But I'm happy with not roasting at night anymore. I don't remember who did these changes to begin with but you can now change them yourself. I haven't been woken up with the heat so high I was sweating. So that's a good thing. Here is what it looks like....

[Adridreamer11]

Wait. What do you mean. I need more clarification!! Lol. Please I am desperate 

[Magicalgirl]

This did t solve my problem 

[Dannynjoni]

This needs more attention on this page. This is the only thing that worked for us and seems to be to fix. Thanks so much for posting this idea. It wasn’t very difficult to find the schedules that needed changing using your laptop.

[dadude]

This is getting old… and a bit dangerous.  Google needs to fix this.  

[MoneyOverMen]

Check my reply. The answer is in Settings. I don't know how it got there where these temperatures are like that, but it can be changed. 

[Divamac · Accepted solution]

UPDATE:  Google support said that the Nest requires all wiring to be solid copper, not stranded wire. My main wire from the furnace to my thermostat is stranded wire. So instead of paying $250 to have a new wire run, I am opting to replace my Nest with a different thermostat. I’ve had all the automations and learning turned off for more than 2 years, so I’m not losing anything but the aggravation of a thermostat that’s trying to boil me alive. 😂

im attaching some photos of my chat with Google in hopes it helps some of you resolve your issues. 

 

 

 

[Amddrafting]

So for 3 years my Nest works fine with Vivint, but as soon as google takes over suddenly I need new wiring? I’m not buying the excuse, sorry.

[w3eds]

That is utter nonsense - it's Google almost trolling you. Is this mentioned in the manual anywhere? 

[Divamac]

For me at least, it was not the Nest. I’ve now had 4 other thermostats now, and I still have the same problem. My HVAC company has never seen anything like this. I got a new HVAC system at the time I got the Nest. The house was not required for the new system. It’s likely I’ll need to run all new wiring to fix the issue. We’re still troubleshooting. 

[Red14Blue16]

Looks like the only fix is to buy a different thermostat

[Andnig]

I just started having this same issue right after I installed a néw unit. I am blaming the AC install company only to read these comments with the exact same issue. I spent a lot by my standards to buy and professionally install this. Someone has to give accountability for this. Just for all of us to say buy a néw thermostat while google gets richer is not fair at all

[Divamac]

My issue started after a new HVAC install, too. That’s also when the Nest was installed. I’ve now had 4 different (non-nest) thermostats and had the same issue. It’s not the Nest. It’s something to do with the HVAC system or wiring. My HVAC company has been to my house 6 times since December troubleshooting without a solution yet. 

[Divamac]

For anyone following, the company that installed my new HVAC system 3 years ago (along with my original Nest) replaced the Nest with a bare-bones Honeywell unit and the problem didn’t go away. So the Nest was never the problem. They’re coming out to do a detailed diagnostic on their install. They suspect I’ll need all new wiring. 

[w3eds]

OK everyone - I had this issue and changed lots of settings to no avail. There is clearly some undisclosed setting that Google won't admit to where it's automatically deciding it knows best. 

On my schedule, we have the heat come on in the morning for about 1.5 hours and then it should switch off. In the evening the same, on for about 6 hours.

However, the heating was coming on in the middle of the night, and also the day, and according to the schedule it should 'not' be on. 

My assumption is that the Thermstat is not seeing the end of the Schedule and will try and maintain the last temperature that was present on the schedule. So if the temp was set to 20 degress celsius (UK) then it will continue to look to maintain this regardless of the schedule settings. 

My fix was to add a new temp to the end of the morning and evening 'sessions' and drop this down to a temperature well below the normal household temp. In this case 15C for me. Since doing this, the heating has not come on once outside of the scheduled time.

It's a workaround to a bug that cleary exists, which is probably related to the Nest trying to be to clever for it's own good.

Anyway, give that a try and it seems to work just fine for me.

BTW - in answer to a question earlier, you can't change the schedule for everyday by just changing it for one day but you can copy and paste the scedule from one day to the others. On the main schedule screen, press and hold on day you want to copy (IoS) and you should see an option to 'copy' appear. Press copy, the press and hold on the day you want to 'paste' to and you can drop it in there. Then just press and hold again on another day and 'paste' again.

Hope this has helped.

[Amacrae]

Hi,

I tried all that too and it never made any difference as I think it's a time zone issue as it thinks 1am is my 6am so when I added the extra settings at 6am to stop it increasing the temperature it did nothing. I was going to move my 6am setting to see if that worked, but just as magically as the issue appeared it has now disappeared and I no longer get the heating come on at 1am. 

It's been a couple of weeks now and still no issues, and I did nothing and there have been no updated to the app settings , the app or the software on the NESt thermostat.

I still believe this device is over priced and does not not replace the manual system well enough, especially in the UK where you want to be able to set an off and on time based on time as well as temperature. Anyway come summer I will swap it out for a standard programmer and manual thermostat that I know will work and is easy to diagnose and fix compared to this heap of junk!

[ECollins86]

One of our nests randomly set to 90 degrees in my four month old’s nursery last night.  Almost called the hospital when I realized it at 2AM.   Indoor heat strokes are a real thing for babies. This is a truly dangerous problem.

[Andnig]

I will be honest here. I called Nest support and they had me clear my settings. They then had me check the logs and insisted someone was messing with the thermostat. I was reluctant to believe it but I have two young kids and some friends were over for the holidays with two more kids as well. So I followed their instructions and locked my thermostat and set that no one can make it go above 78 or below 70 but me with the app. I have not had a problem since and it’s been over a month. Knock on wood that it stays this way.

[jchilc005]

12° outside 4am and our AC is on!!!!! I hope it didn't screw anything up because our unit is covered. 

[Uglypcs]

I have also had this issue. First time in the summer, cooling mode changed to 50°. Tonight my whole Florida household awoke to the smell of something burning.  Heat  mode had changed to 90°.

[Badgerjww]

My thermostat just started doing the same thing!  It almost overheated my old boiler because the heat decided to change to 90! What is going on?! It has worked perfectly for 5 years up until now, so i am not buying that it needs to be re-wired.  GOOGLE WHAT IS GOING ON?!!!

[Adridreamer11]

I reset both my systems back to original settings like if I was going to sell them. And so far so good. Best of luck