Rural King has had 12 oz cans of 134a for $ 4 each for several years now. I have used it in several cars and

had no problems.

If you're dealing with an incompetent shop, that's a different problem; find another shop. You shouldn't have any problem getting the few pounds of R-12 you need for $100 or so if you ask around some. There are thousands of R-12 systems still out there that leak a little into the atmosphere all the ...

What do you mean common sense ? Common sense would have been to stay with R-12.

That high pressure is low for that ambient temp. Are you sure it has enough refrigerant in it ?