I was quoted $2,300 to replace my 3 1/2 ton A.C compressor. A Google of
A Copeland Compressor shows a cost of $625. Is $1625 for labor & freon
Excessive?? What is reasonable?

It is a good price , go for it , don't be cheap for professional repair .
They have to give you warranty usually 5 years on compressor , also is good to have extanded warranty from service man good luck :D :D :D