Hello nest_user_ca,
Thank you for taking the time to let us know about your inquiry. Let's sort this out!
The placement of wires in the thermostat can indeed impact its functionality. In a typical thermostat setup, the white wire is associated with heating, while the O/B (usually orange or blue) wire is for the reversing valve in heat pump systems.
If the white wire is in the OB slot, it might be causing a conflict in signaling. I would recommend checking the wiring diagram on the Nest Thermostat and ensuring that the wires are correctly placed according to your HVAC system's specifications. If the issue persists, share with us a photo of your old thermostat and Nest Thermostat's wiring setup.
Keep me posted.
Regards,
Mark
