Before and after I had the refrigerant toped off the condition was/is the same. When the a/c cut off there is no voltage to the low/high pressure sensor. If the system was over filled causing high pressure I would still have voltage on the one side of this switch.
My guess… the voltage from the CCU to regulate the temp inside the car. My thinking is the CCU turns the compressor on and off to maintain the temp. For some reason it decides it cool enough inside the car and turns the compressor off. After the car sits sometimes just a few minuets wile I run in the store it work fine. Is there a sensor inside the car?