If you plan to use this for printing PLA it probably will not work. The issue is not with PLA layer cooling so much as it is cooling the throat of the extruder. A fan blowing across the print area in this fashion will not cool the throat enough and you will still get swelling and jams. You should look as Scobo's thread. He did a very easy mod by adding a few heatsinks and moving the existing fan slightly lower and is now able to print most filaments.
Of course layer cooling is important as well for PLA but this set up will still not accomplish that either. All you will do with this is keep the inside of the printer at room temp and make the entire print cooler then the last few layers laid down which will cause warping probably.
But since you have it planned this far go ahead and try it. I might be wrong.
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