here is picture of old tstat. Maybe hard to see, but white wire was W2, blue wire was O/B. Green of course was G (fan), red was RC, and yellow was Y. This is dual system with gas heat as aux. I wired to nest using Green - g, white - W2, blue - O/B, yellow to Y1, and red to RC. Completed setup in equipment, and try running system but outside unit does not run? Any thoughts. I realize the old thermostat was only wired with 5 wires, but all the diagrams I see for nest with heat pump show at least 6 wires.
Look up the old T stat find the manual with wiring info to make sure what the left hand terminals are for S1 S2 .
I don't see a common wire so see if there is an extra color wire in the cable you can use for common.
Rc is + for the a/c heat pump, Y gets + power when tstat asks for a/c and turns on outdoor unit, o/b is the control that switches the heat pump from heat mode to a/c mode, that is normally orange wire.
post pics of the connections at the indoor unit and outdoor unit.
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.