I am looking into buying a 97 b2300 with 136,000 on it, but when I test drove it the ac blew hot air, the guy says it just needs a recharge and that he has to charge it every year or so cause of a possible leak. First, what kind of refrigerant does this truck take? And second, if I have to diagnose a leak or replace ac parts, how difficult\costly is this going to be? Thanks