I tried the sealer in my W210. It did not help.

I ended up rebuilding the entire system after the compressor seized in the spring of 2016.

http://www.peachparts.com/shopforum/diesel-discussion/377507-w210-compressor-seized.html
I have not had to touch it since (as in I have not added any refrigerant to it) and it still works flawlessly even in our brutal SC summers.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech