DIAGNOSIS: The O/B setting is incorrect for your specific heat pump. This setting determines whether the reversing valve energizes in Heating or Cooling mode.
FIX: During initial setup or in Menu > Settings > Equipment > Heat Pump, you must select the correct O/B setting. Most Rheem and Ruud systems use O (energizes in cooling). Most Carrier, Bryant, and Trane systems use B (energizes in heating).
IF THAT DIDN'T WORK: Confirm the physical wire connected to the O/B terminal on your Sensi baseplate matches the setting in the menu. A mismatch here will cause the heat pump to run in the wrong mode.
HEADS UP: An incorrect O/B setting can cause your heat pump to blow cold air when heating is called for, or hot air when cooling is called for. Verify with your original installer or heat pump model documentation.