I have a compressor on a 1985 190E with the same symptoms. I can force the compressor on however after a few seconds of running, the fuse blows. I have traced to what I am guessing is a problem somewhere on the compressor however ran out of troubleshooting time this weekend.

Tons of current is flowing to blow this fuse, nothing inside the Klima on its control side can withstand such current without smoking. Most likely it is the clutch coil. Shorting terminal 5 and 7 in the Klima socket can distinguish between the coil and the Klima possibilities. If it is something shorting in the Klima relay only, the fuse will not blow when 5 and 7 are shorted.

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Saumil S. Patel