Heat not working-a/c works; manual set states it will start in 2+ hours

[red310]

a/c works; heat stopped working--then started again; reset to factory default and now when I manually set its states it will change in 2 hour plus; won't come on at all (2 years old with no problems)

[zoeuvre]

Hi red310, 

Yikes! I'm sorry to hear that your heat is not working with your Nest Thermostat. Let's see what's going on. A few questions: 

1. Are you located in North America or Europe?
2. What type of Nest Thermostat do you have?
3. Is the Nest thermostat newly installed?
4. Does the thermostat screen indicate that it’s actively calling for heating?
5. What type of furnace do you have? (gas, electric, etc.)
6. When did heating last work?
7. Did heating ever work with the Nest thermostat? If not, did the heating work with the previous thermostat?
8. Did you turn off the power to the HVAC system?
   • Did you recently turn off any breakers?
   • Have you recently experienced a brownout or blackout?
   • Is there a light switch near the heater that controls an outlet?
9. Did you select the correct fuel type?
10. Do the LED lights blink on the HVAC control board? If yes, locate the light.
11. When was the last time you changed the furnace's air filter?
12. Have you experienced extremely cold weather lately?
13. Is this the first notable temperature drop of the year in the area?

Also, please gather the power readouts of your Nest Thermostat's VIN, IIN, and PS-* under Settings > Equipment > Power Info if you have the Nest Thermostat 2020 and Batter, VOC, VIN, and lIN for Nest Learning Thermostat or Nest Thermostat E under Settings > Technical Info > Power. 

Keep us posted.

Best,

Zoe