Check out this info on JimF's webpage:

http://pages.prodigy.net/jforgione/AC_Seal.html

He had an evap leak on his W140 years ago, and used a stop leak product, and it worked.

Don't know if it will work or not for your car, but if you are going to have to replace your evaporator anyway, it might not be permanant, but it might buy you some time.

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".