1990 300SEL

AC has been converted to R134. Worked fine last year after a system flush and charge.
This year is hottest summer ever and it was blowing warm, had it charged up, worked fair for an hour, then compressor stopped working. Let it sit 2 days and it worked again (marginal) but not great. Had it checked and topped off, no problems found. Today in high 90's and city traffic compressor turned off again.

Seems when outside temperature is high 90's, it doesn't blow cold, the engine temperature goes up to between 100 and 110 (fans work), and then the compressor cuts off. After it sits for a while and the engine cools down, the compressor works again. Blows almost cold when the outside temperature goes down to low 80's or below.

Is there some type of temperature sensor that keeps turning off the compressor when the engine gets hot?

Thank you in advance for any help.