You ought to let it run for a couple of days first; as someone said,
you not only have to cool the air but also the ducts themselves and
anything else the air touches before it reaches your vents.

If the ducts run through the attic you also might to have a look to
see if something came loose during the winter, or if some creature
knocked a hole in the ductwork. A couple of years ago a worker in the
attic (working ON the A/C!) knocked a fitting loose and there was a
gap where the duct attached to one of the vents.

Shaun Eli
www.BrainChampagne.com

Copyright 2010 by Shaun Eli. All rights reserved.