Sorry its taken me so long to get back. I though I was having trouble uploading pics from my iPad and I'm rarely on the desktop. Turns out I can't figure out how to upload them from here either. :R Here's what I figured our: Dometic pkg'd the wrong thermostat and electronic control box with the Heat Pump thermostat. They sent us a replacement. It went together, with no "which wire, where?" questions after that. The small paired red wire hanging down from the unit is to the outside temp sensor. Its only on Heat Pump models. It plugs in next to the clamp.