I would like to ask the Honorable List for extensive advice on the subject of the A/C maintenance and charging.  I would like to do it myself instead of going to a shop every time I need a system serviced or change a pump or change over to a different gas, etc.  I would feel better if I knew all that I have to know about our vans' A/C system.  
I would like to read about the principles and whatever it takes to aquire the knowledge.  So, please enlighten me.
Zoltan