Carrameow is working on a W124. And yes, the evaporator is suspect. I had a 1987 300E on which I spent $8000 in repairs in just 2 years (major A/C work 3 times) and still sold it with a broken air conditioner because the evaporator spring a leak.

Yes, it is a long job to change an evaporator (the part behind the dash board) on a W124 and I refused to do it. The procedure is pretty well detailed in at least a couple threads on this board. Just search for "300E evaporator."

Carrameow, much of that added complexity is to protect the serpentine belt. On the OM616/7 and earlier engines, if the compressor locked up then it would shred the A/C belt and you'd keep rolling along with no problem. But on the OM603 and later engines, if the compressor locks up then you can loose the one and only serpentine belt and you're stranded. So they put the electronics in to detect a compressor lockup and release the clutch.

Another problem with the car in question is that the Nippondenso compressor has teflon coated pistons which spread "black death" throughout the system when the compressor fails. Go to aircondition.com and look up black death. Not pretty at all, and not easy to get rid of. Sorry, but I'm not optimistic that you'll get the A/C working in just one weekend unless it is something as simple as a leaking schraeder valve.

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Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
Chain Elongation References