Pressure switch I had to change, because I still had the old one with 3 connectors.
Cars before 2/89 have three pressure switches mounted on the dryer. A high pressure switch, a low pressure switch and an intermittant pressure switch. The updated design only has 1 switch that is used for low and high pressure detection. The intermitant pressure switch will no longer be used.
http://bmwe32.masscom.net/johan/airc...con_R134a.html