Thermostat blows hot air on cold setting (heat pump)

[Micah_S]

I've got two Nest thermostats on heat pumps in an upstairs/downstairs configuration that I've been running ~6 years. Setup is correct because both thermostats/heat pumps have correctly run hot/cold settings, but when spring comes the Nest will occasionally (3/4 out of 6 spring transitions) run hot air on the cold setting. First time Nest support sent me replacement parts. Later I was able to swap thermostats on the other heat pump and it "reset" and started running cold on the cold setting. Lately I've been running heat/cool all winter thinking this will get some cooling cycles in and prevent this problem, but now I have an issue with one thermostat running hot on cold. I can confirm by testing: I can get the "bad" thermostat to blow hot on cold settings on both heat pumps, and I can get the "good" thermostat to run correctly on both heat pumps. I'm currently cycling the good thermostat between the two heat pumps; I have not yet tried to reset the bad thermostat to factory settings, if that's an option. I really don't want to chat with Nest support for 2+ hours again.

(my issue seems similar to this thread, but there is no answer here. in another thread the member simply replaced his thermostat.)

Questions: Why does this happen? Is there any solution other than throwing away this thermostat and buying a new one?

[K_Lawson]

I’m having the same issue with my 3rd generation Learning thermostat. I haven’t seen any promising insight. It seems like there are enough people having the same issue that support would be aware. I am six days outside of my warranty period and just started experiencing this. 

[EdwardT]

Hi folks,

Thanks for reaching out and I'm sorry to hear that you're having an issue with your Nest Thermostat. I'd love to know more about what's happening. To isolate the issue, please let us know how your Nest Thermostat is wired so we can investigate further.

Thanks,

Edward

[MelbaDT]

Hey there, 

Checking back in ― still need our help? If you do, please provide the photo of your thermostat wires so we could keep the ball rolling. 

Best, 

Melba

[MelbaDT]

Hi, 

I haven't heard from you in a while so I'll be locking this thread if there is no update within the day. If you have any new issues, updates or just a discussion topic, feel free to start a new thread in the community.
 

Best, 

Melba

[Micah_S]

I decided to buy a new thermostat because there seems to be no support on this issue. I still have my old thermostat, in case there is anything worth trying that may resolve the issue. We had our HVAC tech come look at the unit and it was working fine; we heard the unit "clicking" and we thought there was an issue with the unit, but the tech said the clicking we heard was the unit trying to switch off the heat cycle. He indicated this was due to a faulty thermostat in his opinion, which confirmed our testing (our working thermostat performed fine on this unit, as well as the new thermostat; no wiring changed when installing the new thermostat). 

It appears that this is a bad/faulty/"dead" thermostat, but again am willing to test out other methods to make it work.

[Micah_S]

Hopefully this will help with a solution for someone else:

 

[Ryan_G]

Hi Micah_S,

Thanks for sharing your thoughts here in the Google Nest Community.

I'd like to jump in here and check on how your thermostat is doing. Let us know any updates and we'll be glad to talk about it and help you.

Best regards,

Ryan

[Ryan_G]

Hi Micah_S,

I just wanted to follow up and see if you're still in need of help. Please let us know as we would be happy to answer any questions you may have. 

Best 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