I've got a brand new R4 compressor installed with a new condenser, drier, orifice tube, and o-rings. I vacuumed it down and started charging it with R134a. Once I got a partial charge in the system, the clutch started slipping and making this godawful screeching. I really don't want to have to send the stupid compressor back for warranty replacement. Is there something I'm missing? Maybe there's a way to adjust the clutch so it actually engages properly. I just don't know what it is. Any help would be appreciated.