The A/C comes on, but won't turn the heat on

[red310]

THE NEST TURNS ON THE A/C, BUT WILL NOT TURN ON THE HEAT

[zoeuvre]

Hi red310, 

Yikes! 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, gather the power readings of your Nest Thermostat. For Nest Learning Thermostat and Nest Thermostat E, go to Settings > Technical Info > Power (Battery, VOC, VIN, and lIN) and to Settings > Equipment > Power Info (VIN, IIN, PS-*) for Nest Thermostat 2020. 

I'll look forward to your response. 

Best,

Zoe