Most A/C jobs require professional repair these day's, unless your pretty familiar with auotmotive a/C systems. Not to mention the equipment, vacum pump, refridgerant recovery systems, license to purchase refridgerant. No you do not have to convert to 134A. Having said that some shop's just wont repair unless you convert.Be aware of some of these so called conversion's in a can they can be down right dangerous. Do your homework well before using or letting someone else use it. Hope this help's.
auto\hydraulic mechanic 20 yrs