<<Larry, thanks for the words of caution about jumping to conclusions, however, even on the remote chance it is NOT the evaporator, what ever is leaking is not accessible under the hood or the A/C shop would find it, wouldn't they? >>
Not that easy..
If they put dye in it when it was recharged , they would have a better chance of finding a leak, but you do not mention this..
What Larry is saying , and I agree... Put the dye in and then look for leaks .. an under hood leak w/light will now be more evident and easier to find..the dye is not just to test evap.
It will test the whole system...
I have seen many under hood connection leaks that showed after dye testing that did not show with a snifer or observation.
Many times , the recharger just visually looks for signs of oil at connections and calls that a leak test..
I would try the dye..and give it a couple of weeks to show..
A high side leak will show up more when a/c is on [ more pressure in that part of system] and a low side [evap] , tends to leak more when a/c is off..[ more pressure in evap when a/c is off]
[The reason for my other post of snifer after leaving car overnight for testing evap]