1993 300e with 134 freon. Holds a charge and blows cold for about a month.

Where do I start?

I've heard talk about a dye used to find the leak. Where do I buy that? UV or non UV? Then I suppose replace the O ring thats bad if I'm lucky, evacuate and new dryer?

I feel lucky owning the only Mercedes car in this small Kansas town! NO one wants to help!

Comments appreciated.