I didn't go to HVAC school, but I have been moonlighting w/ a friend's HVAC business since 2002 for the exercise & appreciation of hard labor. That was well & good, and in time I was making decent, seasonal money working for someone else when not servicing IT needs of SB clients. Around 2008, as many of my clients were closing shop, I crossed paths with a "controls" guy and he showed me how to meld the technical & the labor to make as good money, if not better, as sitting behind a keyboard and playing whack-a-mole security full-time. Between pulling runs, provisioning controllers, solving failures and putting it all into comms I get all my mental, physical & financial needs met. I couldn't recommend it enough for anyone tired of the sedentary life at the keyboard. The only downside is I am still reliant on corporate managers & NOC engineers who have no clue how their products work in the field. YMMV.
TLDR: Get the HVAC skills, then go into PLC work.
Edited: 3rd sentence for context.