If you're worried about the evap (I know I would be since it's a W140), bring a sniffer with you, if you're unsure. Run the A/C for a few minutes, then shut it off and stick the probe near the condensate drains and/or the interior vents. You should easily be able to pick up even a tiny leak.

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280