A/C compressor intermittent 300E
 

OK, I've tried a bunch of things...but still I have a funky A/C operation.

I connected the A/C hoses, observed the static pressure (>80PSI),
and after warming up with A/C on max, have high side of 250 and low of 50
PSI. I added about 14 oz of refrigerant until the bubbles nearly stopped in
the sight glass. A/C outlet temp was in the range of 55-degrees.

I went tooling to the restaurant and stores. Once the car sits hot for
some time, the A/C clutch will not kick in, so the compressor does not
run/operate. Overnight, and the A/C works.

Ideas? Fuses OK. Reasonable cool (but not cold) air. The return line sweats
and is cold like it should, but not really frosty.

i think my a/c is about right when the low pressure is about 30-35 at 90 degrees ambient , 1500 rpm's

Need low side pressure at 35 psi at 2k rpms. dont worry about high side unless you suspect the compressor is dead. If you have bubbles when charged may have too much air from leaks in system may need to empty, evac and refill.

there is a speed sensor on that comp clutch and if the belt is a little loose[common on those engines as belt tensioner gives up regularly]when you restart hot the speed sensor will kick off the clutch and won't try to restart until you stop and restart car.this is controlled in the a/c relayif,when hot you start with a/c off and let the idle stabilize then turn on a/c you should find it will start to run and not be an issue until next stop.