What about the cost of the time you would put into the class? Surely that brings the total effective cost of the course to far more than $115, to acquire a skill you're unlikely to gain much from (unless you want to learn it for its own sake or become an AC tech).
If you pick up some general electronics and mechanical skills, that will go a long ways helping to understand what might be wrong with your car, or around the house.
Just last week I replaced the inducer fan on my natural-gas furnace, with no prior training other than watching a YouTube video. I was able to deduce that the inducer was the problem in the first place, because I wasn't afraid to take off the cover and carefully observe what the furnace was and wasn't doing. And understanding at a high level how furnaces worked in the first place.
Of course, to do that, I was able to draw upon decades of experience with all kinds of systems. My training started as a child by observing and helping my father in his workshop. Even so, just having some basic, basic skills and knowledge of debugging [1] can go a long ways to isolate what the problem is and then see if it is something you can fix yourself.
