Complete A/C rebuild Q

High pressure is the smaller lines from compressor side marked 'D' (discharge) .
Low pressure is the larger lines to compressor side marked 'S' (suction). The capilary tube from expansion valve is nitrogen filled copper . Dont kink it ! That is a tappered seat type seal point (I think). Be sure to pull those cone shaped screens from the expansion valve and clean them if you not replacing the valve. Might be just one or 3 screens stacked together in there.