I wanted to ask...is there a final fix to the air conditioning when is just loses its cool? of course mine is not cooling like it was and so I think I have to take it in. ('16 V6)
Sure there is. What it costs is the question.
15/16 were very prone to have the evaporator leak. That's a dash out repair and between $2000-$3000 to have done. The part isn't expensive but the labor is extreme.
Stuff under the hood is easier and usually DIY repairable though a few specialized tools (vacuum pump & manifold guages) are needed to do it right.
A simple black light can help identify leaks.
Do some internet research for information on how ac systems work to demystify the systems. There are also videos on diagnosis/repair/replacing most parts.
All in all, it's not that difficult - well except for the dash out bit...
Well, I am familiar with how it works, I just haven't kept up with what may be cures for the Mustang issues. I want to fix it ONCE if it fails again the car is gone. I'll go back to older stuff that I can fix!
Well, your first step is to find what has failed.
If it's "just" leaking it can be anything from a leaking Schroeder valve to a bad evaporator.
The ac on a mustang is no different than any other car really. Sure the first gen S550 was prone to evaporator leaking but so was my old '98 Grand Cherokee or numerous other Chevy, Dodge, Fords, etc.
Sadly blend doors are another failure point across numerous brands but your brief description of "losing cool" doesn't lend itself to indepth diagnosis over the internet.
So, on my own I found that the switch was the problem. I cleaned it and used it a bunch and now, Bob is my uncle! (or as some like to say, "I never looked back"....