HVAC Design

Hello everyone, I am currently a BIM Designer (Plumbing) with my company right now. We only handle Plumbing, as a Mechanical Engineering graduate I want to learn HVAC design, designing HVAC systems, chillers, bigger units you name it. How do I get started with all that? What sites, videos online learning do you all recommend? I am trying to boost my skills to actually call myself a mechanical engineer. Thank you all.