I have an electric heat pump system. It worked fine with the original thermostat. I switched over to nest learning third generation and it's only blowing out cool air. Attached are two pics of my original wiring and my nest wiring. I can't get my heat to turn on. I switch B to O for heat pump setting based on troubleshooting recommendations. I've been looking through all the forums but no answer. I'm not sure if it's because of the heat pump or a compatibility issue.
Your system uses the B option for the changeover valve and you need to change that in the Nest.
Maybe the wiring at the terminal block on the control board in the furnace/air handler is wired a little differently. Take a look there and see if the wire labels match up, post a picture if you will.
Thanks for reaching out here in the community.
I'd like to jump in here and check if you've seen Patrick_Caezza's response. If you have further questions, let us know by replying to this thread.
We haven't heard from you in a while so we'll be locking this thread if there is no update within the day. If you have any new issues, updates or just a discussion topic, feel free to start a new thread in the community.