how do I get into real commercial

I work for Lennox Nas the pm company with extra steps. how do I get into a company where I can work on more than 15 tons rtus that come broke from the factory and a company that is will to teach me the thing I need to know. I wanna work with chillers and bas but know next to nothing and have little experience and my company shows not much interest in training me in anything. do I need to go union or try trane or York. I just wanna learn and be equipped with the tools to do so.