After you try the advice given here, if it doesn't match to your
satisfaction ( and there's a fair chance that it won't) , consider
this as Plan B.....
Buy a vent grill for a buck or two from Home Depot, the kind
that would be used over an inlet/outlet to a heating/cooling
system, and put it over the bad spot.... It will appear to be
just another vent for your air condx, and will cover a
myriad of sloppy texturing......
Andy in Eureka, Texas