When service personnel say things are good or look great but do not specify any quantitative values, I would be suspicious. What is the suction pressure and discharge pressure when the compressor cycles off? If the suction pressure is around 50 psi then the evaporator is not reaching design temperature which is 32 deg F.I had a certified mechanic flush, replace the schrader valves, vacuum down, confirm it held vacuum, then charge according to the car's capacity. He said it looked great on the gauges, and when he was done, it worked better, but would still cycle before it got cold enough
If the system over pressures and the high pressure transducer switch is signaling excessive system pressure to the PCM (powertrain control module) then the PCM disengages the compressor until the discharge pressure reaches a safe level before allowing the compressor clutch to re-engage.
Now if you can verify that the suction and discharge pressures are within the operating design range for outside temperature, then its possible that the evaporator temperature probe is malfunctioning and giving a false signal to the PCM and causing the compressor clutch to disengage prematurely.
The resistance of the probe is proportional to the probe temperature. At 50 deg F it should be around 9950 ohms and at 100 deg F is should be about 2912 ohms. At 32 deg F the resistance would be about 12472 ohms. If the probe is giving excessively high resistance values above its design range, this will fool the PCM and cause it to disengage the compressor clutch.