Did they charge it up and put dye in it and verify that fully charged the system works and allow positive verification with a black light for the diagnosis.

I would get a second opinion of any evap diagnosis that isn't verified by a dye test. My best guess is there are at least twice as many evaporators replaced to CYA as for real leaks. it is a hard call as it is no where near being viewable. The dye gets carried out of the drains by the water and is proof positive of a diagnostic. Once inside the case the absolute leak can be verified with the dye, sometimnes preventing further problems.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician