So an hour of so of googling comes up with conflicting answers. The SAE says to keep the temperature low and slow the fan speed as necessary:
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Initially the A/C should be set for max full cold, highest fan speed. As the interior of the cabin begins to reach some level of comfort, reduce the fan speed to the desired comfort and noise level.
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https://www.sae.org/standardsdev/tsb.../mobile_ac.pdf
But further research indicates it is more complicated:
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Some cars simply clutch the compressor on and off constantly to maintain the correct refrigerant pressure and, consequently, the appropriate cooling. Others use variable displacement compressors, and still others use a throttling valve in the refrigerant line. It gets more complicated: Some vehicles, especially ones with automatic temperature controls, use air heated in the heater core to blend with cold air from the evaporator to control the temperature of the outlet air. And if that sounds like it's inherently inefficient, it is.
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https://www.popularmechanics.com/car...12178/4281039/
I know my older Toyotas with rotary dial temperature controls would cycle the compressor on & off (you could feel & hear the compressor cycling on - especially idling at a stop light). So that's why I always ran the fan on high (to maximize "wind chill" while minimizing compressor run time).
I don't feel my prius cycle the compressor, but it runs on electricity rather than off the engine. I think it uses a variable compressor, but maybe it blends with heater instead? I'd think they would go for maximum efficiency though and avoid that waste. I'd assume your ionic does likewise?
Edit: You are right! The Prius does have a variable speed compressor, BUT even with that Toyota still uses an "air mix damper servo" to run some of air conditioned air through the heater to achieve the desired temperature. Crazy!
