some misinformation here. if a change over is done correctly
there should be very little differance. most areas do not require repairs if you have a leak. not in my area in calif. i'm in the central valley that is in the 100's during the summer and don't have any problems with change overs. don't use alternative gasses. most shops will either refuse to work on them or charge a lot of money. i check all cars. if they have alternative gases i charge almost $200.00 more to capture that gas and send it to be destroyed.
the fact that you say that it doesnt cool when you go into the sun makes me think you have a control problem. if you mean when it gets hot then your system needs to be checked.