Is something missing from the top of my AC compressor?

Washer pump relocated temporarily during my rodent hunt - new to me car cleaning....Noticed waht appeared to be a fastener fastening nothing.....

Rob M
Concord,MA
'85 300D (non-CA)

Attached Thumbnails

 

Hard to say from that angle, but could that bolt be the tension adjustment for the drive belt?

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1991 M-B 560SEL Arctic White/Grey 99,000 Miles
1987 M-B 300SDL Ivory/Palomino 229,000 Miles (sold but never forgotten)
2006 Volvo XC70 Blue/Beige
1999 Porsche Boxster Arena Red/Savanna Beige
1986 Porsche 928S Goldweiss/Brown

Perhaps....I will look more closely as the oppotunity arises..Thnkas for the thought.

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Rob M
Norwich, VT USA
1980 240D Euro delivery 4 speed manual silver/blue
~160K miles