when I run the AD595 test project included above, I get the correct temperature values
The demo code doesn't use analogReference().
As far as the analogReference(), it was there when I began with the code so I am unaware of its functionality.
It was where? It was not in the demo code. Why did you put it in the real code?
How can I test if I have access to that library?
Go to where you installed the library. Check the properties on the cpp file in that directory.