Restoring AC

Our local NAPA store sells a product called "Freeze 12" It is a direct replacement for the old r-12. Its only about 12.00 a can here. R134A wont cool as well, but it will work. I have read somwhere that if you use r134a, you need to wire in a high side safety switch. Dont know why?

Hmmmmmmmmmm I'll remember that. Nice Dart by the way.