Sparks,
do a search on the subject. I am a DIY and I did it WITH the MB manuals. If you have the time (it took me a week) you are not afraid of HARD work, just do it! You will save BIG $$$. Make sure you have all the parts BEFORE you start. Oh, get a copper core evaporator.
Good luck either way!

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J.H.
'86 300E