It's come that time to recharge the A/C. I've noticed there are conversion kits to change an R12 system to a R134a(new recharge fittings and refridgerant oil comes with most of these). Has anyone changed their system with no problems? If I'm going to consider doing this I would like to know of any hidden issues I might have to deal with. I'd rather do this(the system recharge) myself anyway instead of paying outrageous amounts for a shop to do it.