Originally Posted by BillGrissom

The original R4 compressors are notorious for siezing. Read about it both here and on GM web-sites. The one in my 85 300D seized and gave a plume of smoke under the hood as its clutch slid, melting the connector. Inspect your connector. Unsure about the one in my son's 84 300D. When he pulled in last summer after a 400 mi drive, the AC belt was broke and hanging down, and oil was dripping out everywhere. It had tangled in the pwr steering belt, flipping it over so its "teeth" cut into an oil cooler hose like a chainsaw, wearing a small hole in it. That sprayed oil everywhere, but fortunately still 2 qts left in the pan. I suspect his compressor seized then, though now I can turn it over by hand (I don't mean just the pulley).

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