When I bought my truck a few months ago one of the cons was the a/c doesn't work. Now that it's 100+ degrees outside I really want to fix the ac so I can drive it more. so my question is do I have to switch to the new 134 style because I've been searching on Craigslist and found many people selling r12 freon. I know nothing about a/c so I don't know if the freon is all I need or if there's a certain kind I need to buy or what else I may need. I have a 1983 pickup Any advice will help thanks!!