I got to play hovering homeowner today with the HVAC repair man. He was talking about his years of experience, I didn't doubt, but he decided to get started without many of his basic tools, so I was running back and forth to the thermostat. He finally gets his tools that allow manual control. I tell him what I think is the problem, he agrees, but checks all the things I don't know how to. It ended up being one of those things where I knew more about some particulars than him even though he should know this stuff. Youtube to the rescue, and I'll probably be fixing it myself, since videos showed me he obviously doesn't know how some of the system works.