There's a huge conspiracy in this country to make people think they can do everything themselves. As a person that has been working HVAC for over 10 years and owns real text books that hold information, I can tell you my theory is correct. A few years back a bought a book about doing electrical work, and it was amazing to me how they can produce a thick book that tells you nothing. I've seen some of the home DIY shows, and it's funny to me the first thing they tell you to do is take a sledgehammer to the house, then they won't give you enough information to rebuild it. I'm recently installing a ductless mini split, I had a few simple questions, I watched 2 DIY videos on Youtube and neither one of them address the question. Then, I watched a "professional" video and they never told people to pull a vacuum on the line set. (the refrigerant would be contaminated) they want people to run out and buy all the materials , then quit and call a contractor.