Can you really diagnose your HVAC system?

When we thought about purchasing a new HVAC system, I started doing my research.

I wanted to make sure that whatever HVAC system we bought, had a good warranty to go with it. I was talking to my husband, and he told me to look at the reviews for the different HVAC systems. I should look somewhere other than on the HVAC website. They could be slightly prejudiced and not give any of the bad reviews. While looking through the different web pages, I found an interesting website. It was talking about how to diagnose your HVAC system. I called my husband into the room and showed him the website. I asked if you can really diagnose your HVAC system. He read through the entire website. He then told me that apparently you can do your own diagnosis. There was a lot to read, but it would be easy to pick out the different smells, sounds and peculiarities. Once you have your list, go to that website and input them. They would come up with a list of reasons for those symptoms. They even offered ways to fix the HVAC if they were simple fixes. If not, they recommended calling your HVAC company. He liked the website, and told me to bookmark it. If something happened to our new HVAC system, he would know how to fix it. I think I created Dr. Frankenstein. I could see him now with his handmade HVAC uniform, working on the air conditioner or the furnace. He would probably do more harm than good.