All valves are a bit lower when the patient is standing.
The surface projection is on the left side of the sternum opposite the left 3rd intercostal junction whereas the valve is ausculated on the left side of the sternum at the 2nd intercostal junction. The surface projection is to the left of the 4th intercostal junction whereas the valve is ausculated at the 5th intercostal space in the mid-clavicular line.