The only thing I would add to the post would probably start a whole other thread.

UV dye vs. an electronic leak detector.

You can't really diagnose a bad evaporator without dye, but its so much easier to use a detector for the other components.

Get the knowledge first, pressure check 2nd, find any leaks 3rd.

Then we can start a meanful dialog.

(with 4 or 5 cars to do, I'd get the equipment too) Heck start your own side business to help out the neighbhors and create a tax write off!!

__________________
84 300DT Puke Yellow. Totalled after 438,000
84 300DT Orient Red. 169,000 (actual mileage may vary)
2002 Explorer EB (wife's)