Nest Thermostat heats when it says cooling

[tapuleo]

I've attached a picture of my wiring. When I set it to cool to 76 degrees (it was currently 78) degrees, the system says "cooling" and I can see that my AC unit outside has started up. The fan on my inside furnace starts blowing, and nothing but hot air comes out. The temp keep climbing because the thermostat never gets to 76 degrees, it just goes to 79, 80, 81, etc. I don't know what to do. I have another Nest (newer learning one) thermostat upstairs that works fine. Also, the AC worked fine with the old thermostat, but that one didn't have a scheduler... that's why I got a Nest.

[zoeuvre]

Hi tapuleo, 

Thanks for posting here in the Community forum, and I'm sorry to hear about the situation. I want to check if you are still in need of any help. If so, please answer the following:

1. Did you try using the Help Center or troubleshooter before contacting support? If so, which steps have you tried already?
2. When did cooling last work?
   • If newly installed
     • Check compatibility using the Compatibility Checker tool.
     • Gather all details of the old thermostat & HVAC system.
     • Check the make and model of the cooling and heating system, including the make and model for the, fan-coil or air-handler units.
     • Check if the HVAC system might be using a multi-speed or variable speed fan.
   • If not newly installed, was it working before?
     • Check for any recent changes to the HVAC system or servicing made.
     • When was the last maintenance service and cleaning?
     • Is this the first time you’re calling for cooling this year?
       • If yes, did heating work without issues in the winter?
3. Do you have a photo of your old thermostat wiring configuration? 
4. Do you see a power code on your thermostat?

Keep us posted. 

Best,

Zoe