I'm with Mac on this one.

Air flow in a computer case is one of the things that has surely gotten a lot of engineering attention. Its likely that the very placement of components has been designed to benefit from the designed flow of air through the case.

And due to design patents, you can't presume that just because many computers work differently, this one must too.

Bottom line, if it came that way, I'd leave it that way. Having said that, if you've had it serviced, there is a chance that the fan got removed and replaced incorrectly. The best source of dependable information would be from the manufacturer, or from a certified repair location.