The compressorhas the ground wire running to backof it. But the cluch will only engage if I ground it directly to the battery. DoI need a new compressor or canI ground it somewere else on the car?

 

Which engine is installed in car Olds 350 efi,Cad 6.0,or something else? compressor itself is grounded by mounting brackets to the block.Cadillac used a large braided ground strap from frame to block. Painted bolts and brackets look good make for poor grounds,try adding silver colored star washer to ground eyelet and check condition of negitive battery cable including where it attaches to block.Hope it helps