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Heating in Cool Mode - Heat Pump set correctly

IncompleteBiped
Community Member

I installed a Nest Learning Thermostat on my new house in April 2022 after having had a Nest Learning Thermostat at my previous home for 10 years. My new house has a Heat Pump, which is new to me. Everything with the thermostat has been working fine for over a year now, but there have been some major problems with the heating. 

In August out of no where in the middle of the afternoon, the heated kicks on. The thermostat said it was in cooling mode but was blowing major heat (135 degrees!). After a factory reset on the thermostat, everything immediately went back to normal. About a week later, at 6am, the heat kicks on again while the temperature was set to 68 and in cool mode. I did a Restart instead of a factory reset and everything returned to normal. Two more times, at completely different times of the day, it kicks on the heat when it is in Cool mode. I restarted the thermostat and everything went back to normal. 

Tonight, I tried a restart and then a factory reset and neither are fixing the problem. I had to go buy another thermostat. I'd much rather fix the problem and have my Nest Learning Thermostat back to working. 

I did a lot of Googling, and everything says 'oh, the O and B are switched' but 90% of the time it works just fine with the O set, so switching to B won't fix the problem if it isn't all the time. 

I need help! I would really like to have my Nest Learning Thermostat back.  

1 REPLY 1

Markjosephp
Community Specialist
Community Specialist

Hello IncompleteBiped,


Give props to the steps you have taken! I understand that having the thermostat set to cooling mode while blowing warm air is never ideal. Let's jump in and get it back on track.

Can you run a diagnostic test on your thermostat's Equipment settings? Try activating both cooling mode and fan only to check if they work accordingly. Also, please share with us a photo of your thermostat's wiring.

Let me know how it goes.

Regards,
Mark