Nest Learning Thermostat keeps turning my HVAC on/off

[Ambrose8]

Hello all,

I just installed a Nest Learning Thermostat, triple-checked the wiring scheme (conventional, not heat a pump), and yet the system keeps turning my HVAC system on and off repeatedly.  I've set it to cool mode, desired temperature 85, and despite an internal reading of 75 it keeps running the AC.  But it runs it for a few minutes and then shuts it off, over and over.  I've also experimented with setting it to "heat" mode, turning the desired temp to 85/90 degrees, and nothing happens.

As well, when I tried to run the system tests on it earlier, none of the heating/cooling tests seemed to work, however the fan did turn on.

Any help before I have to return would be greatly appreciated.

Thanks all,

Jeff

[Ambrose8]

UPDATE: It may just be the fan that keeps turning on/off, however even when I have the Nest device set to "OFF", and confirmed in the app as being "OFF", the fan still turns on for one minute or so, off for one minute or so, on end.  Aside from shutting off the breakers to the HVAC system, I'm not sure what to do and am afraid these endless HVAC cycles aren't the most beneficial thing for the system itself... thanks everyone

[EdwardT]

Hi Ambrose8,

Thanks for reaching out. I'm sorry to hear that you're having an issue with your fan. To isolate the issue, could you try removing the G wire and check if the fan would still turn on? If so, it may have something to do with the HVAC system itself.

Looking forward to your response.

Thanks,

Edward

[Ambrose8]

Thanks for the reply Edward; the system did not have a G wire so unfortunately there's no G wire for me to disconnect. 

Thanks again Edward!

[EdwardT]

Hi Ambrose8,

Thanks for letting us know. If that's the case, it's possible that it has something to do with the HVAC itself. I would suggest checking our Nest Pro services so they can take a closer look at your system. You can click on this link to learn more about our Nest Pro services.

Thanks,

Edward

[Ambrose8]

Thanks so much Edward -- reading up on some other threads, it sounded to me like the problem might be that the Nest thermostat activates the fan in order to derive power for itself.  I can't speak to the science behind that/have no idea if that's what was actually happening, but I reinstalled my old thermostat and the problem stopped, so I just returned the nest device.  

Thank you again for your replies here!

[EdwardT]

Hi Ambrose8,

Thanks for letting us know. We're sad to see you go. Let us know if you have questions and we'd be glad to assist you.

Thanks,

Edward

[Ryan_G]

Hey everyone,

I'd like to jump in here and check if you've seen Edward's response. Let us know if you need more help by replying to this thread.

Thank you for your help, Edward.

Regards,
Ryan 
 

[Ryan_G]

Hey there,

Thanks for being here in the Google Nest Community. 

I'd like to bump in here and make sure that you’ve seen our response.
Please let us know if you have any other questions or concerns as I will be locking this thread in 24 hours.

Have a great day.

Best regards,
Ryan
 

[Ambrose8]

Yes, I've been responding in the thread to Edward; I'm not sure if my answers aren't visible but they appear there to me.  Thanks

[Ryan_G]

Hey Ambrose8,

Thanks for the reply.

It's great to hear that you and Edward are still doing the troubleshooting to get everything sorted out.

Let us know if you need anything.

Regards,

Ryan

[Ambrose8]

Thanks for the response Ryan - I think you can freeze/close out this thread if you like though -- again maybe you can't see the full exchange but I discovered from some other threads that the issue could be that the Nest thermostat activating the fan in intervals in order to derive power for itself.  I'm not sure if that's accurate, however when I reinstalled my old thermostat the problem ceased, so I simply returned the nest thermostat.

But I do appreciate Edward's help and your attention here as well.

Thanks

[Ryan_G]

Hi Ambrose8,

Thanks for the reply and we're sorry for the delay.

We also appreciate your patience regarding this matter and we hope to see you here if you have other questions. We'll lock the thread now and you can always create one if needed.

Regards,

Ryan