I am neither an expert nor a professional mechanic. I've have replaced the evaporators on three 124 MBs recently and I'd have to say the answer to your question is mostly likely no. If you can not find the leak it probably is the evaporator.

See this thread.http://www.peachparts.com/shopforum/showthread.php?t=152840&highlight=evaporator

Edited:
Below are a couple of photos of car with dash off, one with evap box and crash bar still in car and the other with them out.