On the non-technical side of this issue. I believe MB originally designed the system solely for their own purposes.
The point is to protect the belt from a seized compressor. As far as I'm concerned this is only a problem during the warrantee period. I can not see a consumer driving a car with a seized compressor unless they figure MB is going to pay for all the problems they creat in the process of not being inconvenienced.
As a result of being protected from such abuse, we (technicians and consumers alike) have been faced with tempermental, intermittant, A/C problems that place many in discomfort. I would gladly give up all I have made fixing these problems to not have to face another of these intermittants on a 95 deg Florida summer day.
I say this after fixing hundreds of them. If I owned one I would bypass it at the first sign of intermittant behavior. I do not do this in the shop, but I would on my own car.
MB has finally given up on this system. They now approach it differently. They put a thermal fuse in the compressor clutch. When the compressor seizes the fuse blows as the pulley heats up. No more speed sensing. Thank You!
Bosch Master, ASE Master, L1
33 years MB technician