If outside air is used and say the temp is 90 outside, you only get say 75 deg degree air no matter what.

Why would this affect what I said? The air would be 75 on low speed,
but on higher speeds it would blow by the evaporator so fast it
wouldn't cool as much.
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Air temperature should really stay the same, BUT the perceived coldness should change. Take a 70 degree day with no breeze vs a 70 degree day with a 15 mph breeze. In the latter, people are cooled by the increased evaporation on their skin.

Fan speed MIGHT make a difference depending on the design, but you really want the evaporator to be just above freezing. With some range of air velocity, the outlet temp won't really change.