If I were you I would learn about the following:
24 volt control wiring
240 volt circuits
convectional heat exchange and the refrigeration system.
Return Air/Supply air/ CFM's and ducting
Because without the basics it will be so foreign you will likely get very discouraged. And the old techs can judge a techs knowledge very quickly and will humiliate you for not knowing anything. I would also examine an air conditioner and how they are laid out and designed.