"$650 to fill the system with R12"

Make sure that you hold your hands way up in the air and look scared, because that's what you're supposed to do when someone robs you at gunpoint.

Shops now can buy R12 for very little more than what R134a costs them. Last year I bought it for $15 per pound, and although I have not checked this year, I strongly suspect it can be had for even less. At their rates they are charging you somewhere in the neighborhood of $150 per pound. FIND ANOTHER TECH. That one is a THIEF!

DO NOT use FREEZE 12 or any other junk refrigerant. I and many others have written numerous times on this forum about the reasons. Do a search, but don't contaminate your system with such trash.

Good luck,