The magic words in SBs reply are "if it's hot out".
It is quite possible to have a/c operation at cool ambient temp/low humidity with a full charge of refrigerent and the system not calling for aux. fan.
The system design is for the fan to come into play when the system is being taxed/burdened. ie- when it HOT.
[ HVAC term is "High Thermal Load" ] , -but hot is fine for us.
With a high demand , the high side pressure increases and
can be kept in check by moving more air accross the condensor.
That's when and what the aux fan does.
And when it is hot out , these conditions are met and the fan is called for...