To do this legally, yes you need to have them evacuate it if it uses R12. R134A can be vented to the atmosphere. They will need to take it down to deep vacuum when you recharge regardless of which type. There is a seal you can replace on the crankshaft in the compressor if you want that is in the front. The rest are O rings and cheap that can be gotten at any decent auto parts store located at all fittings