It’s important to prepare your home and shop HVAC system for the upcoming heat of summer or before it's broken down.
Even though you can handle most of the standard HVAC maintenance tasks on your own, your heating and cooling system is rather complex, and some issues might not be apparent to you. In the same vein, there are more nuanced checks that need to be done occasionally, such as checking for proper functioning of electric components and ductwork as well as the refrigerant (freon) level.
It’s a good idea to occasionally bring in a pro for HVAC maintenance. If your system is new you can probably get away with having someone come just once a year or every other year. For older systems, plan to have professional maintenance performed twice a year—in the spring and then again in the fall.