What determines the duty cycle of the A/C compressor?

[Yaris Hilton]

No, the compressor definitely cycles.

As for whether or not you can feel the difference, well, some people wouldn't know the difference if two cylinders weren't firing. If you pay close attention, and particularly if you measure fuel mileage, you can tell the difference even in huge V8 powered vehicles. But it's proportionately a greater effect as you go to smaller engines with less total power.