So I’d had an issue where the only mode was cooling no heat. Went round and round with Google support on Twitter. Until they mentioned a wire swap. I thought about it and replied it worked before so what’s up.

Took the thermostat off the base, cut the power to the hvac system and pressed down on the w1 tab. Removed the wire and noticed two things. First when they wired it they left a piece of wire insulation hanging. And that the copper wire had a bit of corrosion. So grabbed some steel wool and shined the wire. Re inserted the wire and et voila heating and cooling now work. I replied to Google on twitter detailing what I’d done. They replied “good catch “