Does a non-op aux fan only affect the a/c output at slow speeds, or can a dead fan affect the output on the freeway as well?

I've heard that some electric fans can actually be counterproductive at freeway speeds; they can't keep up with the natural airflow and can actually make less air go into the condenser/radiator...I don't know if that may or may not be the case here, though.

Of course, I need to replace my engine fan clutch as well...

Also, on the parallel-flow condenser, I couldn't readily see what the difference was between that and the serpentine condensers...?