My experience is the system is disengaging the compressor because of low refrigerant not hi head pressure. Pressures are easily confirmed with gauges connected. Are the radiator fans working as designed? With a cooking thermometer in the center vent, whats the outlet temp with outside temp of 100? With average humidity the outlet should be approx. half of outside temp all things being equal. 90 degree day, 45 to 50 degree vent temp. Turning the car off and restarting simply causes the computer to re read the pressures and if in spec allows the comp. clutch to re engage.

__________________
81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.