In the south, if you can define superheat and sub cooling and how to adjust each, you can have a truck come summer. (residential hvac) knock on doors in March, show vocational training, pass drug test, and work cheap to start, you can find work.
I took and passed state hvac contrtactors license test and passed, folks call me at night to come to see them for work.
I took one semester of HVAC a long time ago but every now and then I am able to apply some of it here at home. HVAC in the south is a necessity. I am so burned out on computers and other technology I am looking to do something else. If the budget can survive this year, maybe I can afford to go to tech. college.