Mercedes Benz repair: Recharging the A/C, refrigeration systems, automotive air conditioning

Question
Hello,

I have a 1998 Mercedes C280, with about 98,000 miles, near San Jose, California.  There's a slow freon leak somewhere in the system.  When fully charged, it will cool fairly well for about 2 months, then gradually fail.  It's been recharged at the shop 3 times (once by me, twice by the previous owner).  A dye test didn't reveal a leak after 2 weeks, and there was only minimal loss of freon at that time.

I don't want to pay $150-200 to the shop for them to fill my car with $25 worth of freon.  I'd like to do it myself.  Can you either instruct me on the process, or direct me to a manual or online reference that might help me out?

Thanks!


Answer
Answer:
You must be licensed to work on refrigeration systems.


Climate Control:
http://www.mercedesshop.com/shopforum/showthread.php?t=142408

Automotive repair training book on line, you can download it.
http://www.tpub.com/content/construction/14273/

Automotive Air Conditioning Systems
http://www.familycar.com/ac1.htm

Aircondition.Com
http://aircondition.com/knowledge_base/Home.html