Showing results for 
Search instead for 
Did you mean: 
Replies are disabled for this topic. Start a new one or visit our Help Center.

Nest E Turning On Heat When In Cool

Community Member

I've had a Nest E for at least 4 years and it works like it should; heat does heat, cool does cool, all the learning stuff does it's thing. Definitely wired properly.

I noticed something interesting today, and the thermostat has probably always done this but I've only just noticed. I have it set to cool down to 74°F, and lately it hasn't needed to run because it's cold. However, today the furnace turned on for some reason making heat; house is 69°F according to Nest. I thought there was an issue, but sure enough, the history shows the heat has been coming on once in a while for the past few weeks (the bars are orange). The thermostat is set to only cool (not "auto", if it even has that function), and the screen was blue while the heat was on. A/C unit outside was off, furnace was definitely heating (outside of the unit was warm). Curiously, if I set myself to away manually in the app, the screen goes orange as if it's in heating mode for some reason.

I checked settings for what was going on, but the house temp was at 69°F, set temp was 74°F and it was blue. My "safety" temp for the house is 40°F.  There seems to be no settings for 68°F or 69°F that would trigger something. I thought it might be "Eco-temp" because it's 70°F, but the furnace turned off while it was still 69°F.

Auto-schedule is off, Time-to-temp is "ready", Early-on is off, cool-to-dry is off, sunblock is off, leaf is "ready", airwave is on/ready. Eco temp is set to 70°F, safety temp is 40°F. Outside temp was 49°F at the time, inside humidity is 60%, and Nest knew I was home.


Community Specialist
Community Specialist

Hi KeithGlendale,


Thanks for reaching out and for being a step ahead of us. I'm sorry for the delay. I'd like to know more about it. A few questions: in what country are you located? Do you see any messages or codes in the app or in the Nest Thermostat? Please provide your thermostat's power readings.


You can follow the guide below: 


  1. Go to your thermostat Quick View menu.
  2. Go to Settings.
  3. Look for Technical Info.
  4. Select Power.




Battery: 3.903
Voc: 38.63V
Vin: 38.63V
Iin: 200 mA (c)

Hi there,


Thanks for providing your thermostat's power readout. You have a C wire, and it looks like all the wires are delivering sufficient power to your thermostat. Performing a factory reset on your thermostat would isolate the issue further. I suggest taking note of all of your schedule and on how you want your thermostat to set up before you proceed with the reset.


You can follow this guide to reset your thermostat:


  1. Go to your thermostat Quick View menu.
  2. Go to Settings.
  3. Look for Reset.
  4. Select All Settings. 
  5. Follow the setup process.