IN ctual fact you don't relally need to turn off the A/C. The A/C is linked to the climate control system in the car. If you program 23° in your car, by leaving it on auto, if outside temperature ( and air temperature through cars system) is less than 23°, it simply heats, without the A/C. The A/C compressor only kicks if outside temperature is higher and air needs to be cooled. If you turn off the auto mode, then it will blow23° air, but not maintain the temperature ( therefore if it is 22° and sunny outside, your car will be warmer than 23, and if it is 0° outside, the car will be cooler than 23).
So it only makes sense to turn off the A/C ( Eco mode) if you want to reduce fuel consumption and if you don't care about the exact temperature (assuming it is warmer outside than in the car).
And when you do this, it doesn't dry out any of the humidity, and your car will ultimately fog up inside the windows......
Best to leave A/C on auto, select your comfortable temperature and let it do its work.
Also, did you notice that if you press the center of the temperature knob on the drivers side, it then sets the temperature for both driver and passenger to the drivers temperature, and then adjusts both sides to the same temperature when you adjust the drivers side ( this is cancelled if you set the passengers side separately)....