FOUND THE LEAK!!-- I think......
 

Was changing the oil on my SL500 last weekend thensaw oily residue on top of the A/C compressor area. For the past 3 months, I 've been caring for a minature leak inmy A/C system that a sniffer can't detect. To my surprise, I saw the hoses are covered with "soot" like substance...maybe it's a gasket or the hose itself leaking out.... fresh oily substance colored light brown is the best description I can give... Did I hit a pot of gold????What would you do next?????

a2

The wagon had a similiar small leak. I would notice a small accumulation of dirt attracted to oil on one side of the engine.

I had a hard time figuring out where it was coming from .... it turned out to be a small leak from a power steering hose. I replaced it easily and now the engine is clean.

:-)

Haasman

And it happens to be under the power steering reservior too....
Well, one thing is certain, I'm aiming the "sniifer" on it if the refrigerant goes down again!! Thanks for the input

You may want to go with a UV dye injection to detect that sort of leak. Takes the guesswork and mystery out of it.