does the normal control for the jets work by blocking this air flow? if yes, then blocking it somewhere else won't hurt...
however, if the control for the jets is based on a water valve (3 way) and not on the air flow, then that air is needed somewhere, probably to cool something, and blocking it will shorten life of equipment (perhaps rapidly and catastrophically!)
Maybe someone else knows a little more, but I wouldn't block an air flow unless I was positive that was the purpose of the air pipe to begin with!
Good Luck
Madwil