I had a simmilar problem.... I bypassed the fuse block and added a 30Amp fuse. Then I traced an Amp draw issue with the condenser fan, I unplugged the condenser fan and the fuse stopped blowing, I haven't got around to replacing the condenser fan yet....

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Over 21 years I owned several:
w108
w110
w111
w115
w116
w123
w124
w126
w212