I'm not a chemist, I'm a mechanic. These are just the things I have learned about a/c systems // low side pressure 30 psi =a core temp of about 30 degrees. The biggest joke on new kids is when a customer came in with a a/c problem the old guys would bet on pressure in the system while the car was sitting, ( complaint would have to be not cold enough) and it would always be ambient temp. That's why Freon has been used as propellants in aerosol cans(or something close to that makeup)