Your Regal "W" car has a variable stroke V-5 compressor-- no pressure switch and no need to "jump it" merely pull your vacuum and charge into the vacuum - when system pressure hit 47 psi the ECM will turn on th ecompressor- the 3 -wire transducer on the high side is what tell the ECM to turn on compressor and turn on cooling fan(s) and to turn off compressor if pressur eis too high-- if system is "dead flat" you have a pretty big leak-- need to find and fix leak first- then evacuate and recharge-- most likely leak location is compressor shaft seal- look for oil sling around front of compressor and anything near it....

Also- never try to "jumper" a 3-wire transducer- it can damge the ECM....

Your system will take 2.2lbs/36oz