air conditioning problem of my Toyota Camry LE 1993

Dear smart birds:

I am dummpy bird, especially on cars. But I am learning and I did lots of instrumentation for my graduate degree, :) so I am interested in learning here. I would appreciate your valuable experience and advice.

The air conditioning problem of my Toyota Camry LE 1993 is that it just suddenly stopped working. I want to give a try of changing the "liquid" first. But I don't know how to refer to the "liquid", either in Chinese or English. I checked the user's manual, did not find any hints in the DIY chapters. Should I buy a special Toyota DIY book, I found the information on the back of the manual, a Toyota dealer is near my house if I have to buy such book?

Thank you again!