Always cools even in heat mode with nest thermostat

[Krapol01]

Hello,

I need some help here. We have Nest thermostat. We have the following wiring connection

Y - Yellow wire

W - White wire

R - Red wire

G - Green wire

O/B - Black wire

Earlier we had Emerson thermostat.  Unfortunately we missed the picture of wiring diagram on the Emerson Thermostat.  Now with nest thermostat,  we always have AC condenser on when nest is either in heat or cool mode. Our heating furnace never turns on. We have conventional forced air heating system. I appreciate if someone can help resolving this issue before the winter kicks in. Thank you.

[zoeuvre]

Hi Krapol01, 

Thanks for reaching out to us, and I'm sorry to hear about the situation. I want to check to see if you are still in need of any help. If so, a few questions:

1. Are you able to post a photo of your HVAC control board so we can take a closer look?
2. What type of system do you have? Heat pump or conventional type?
3. Does the thermostat screen indicate that it’s actively calling for heating?
4. What type of furnace do you have? (gas, electric, etc.)
5. When did heating last work?
6. 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?
7. Did you select the correct fuel type?
8. When was the last time you changed the furnace's air filter?

I'll look forward to your response. 

Best,

Zoe