My 240D has non-functional A/C. The Mercedes mechanic around the corner said the compressor and dryer need to be replaced, and maybe the hoses while he's at it. And it needs to be converted from R12 to a newer coolant. His estimate is astronomical.

I can get the parts at a reasonable price online with with the help of a friend can install them all.

Before I start ordering parts and replacing the current system I was looking for some advice on the conversion on whether I should do that. The kit online is about $20 and looks like a bunch of gaskets.

Is there anything I need to be worried about, should avoid, or should be thinking about? Any general information on the A/C system would also be welcome.