Let me get this right, this is your "Son's truck"? It's over 100F. in the Summer? Just a guess, but it's a 1984 with a small-block. Stop-and-go driving? Well R-12 is out of the question, unless you live in Mexico. 134-A? Good stuff indeed! But maybe do like the rest of us when we were young...roll the damn windows down, give that small-block some respect, and learn that life, like one's first wife, ain't easy (or maybe she was, like mine).
Sorry, but I and my siblings grew up in Lake Havasu, AZ. Where it was 115+F. all Summer long, every Summer. My daddy told us if we wanted A/C in our cars we better get better educated, find a better job, or marry a rich spouse, and buy a brand new car every few years.
He taught us that A/C is the weakest link, the most prone to fail, and the compressor is one of the most expensive to fix components in an automobile, short of trans, heads, or engine. So guess what, I went to Auto Mechanic School in Phoenix...because I wanted Air Conditioning in my Cars/trucks. Daddy was a Mechanic, son is a mechanic.
Fast forward to today. I moved away from AZ, went north to the Mountains of Utah. And now when my "Tea-cup kids" whine about how hot it is when it's 84F. and their A/C doesn't work, I tell them "roll the damn windows down, respect that small-block Chevy, and thank God you don't have to saddle a horse every time your Facebook friends want to meet at Starbucks". Really?