That's part of the AC system. I'm not sure where that wire should be plugged in to. I haven't gotten in to my own AC system, yet, but I'd say it's the pigtail for a pressure limiting switch.

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- K.C.Adams

'77 300D Euro Delivery
OM617 turbo / 4-speed swap
404 Milanbraun Metallic / 134 Dattel MB-Tex

Current status:
* Undergoing body work

My '77 300D progress thread