Lowering AC temperature

Hello all:
Last year I converted the air conditioning in my 190 to the "new stuff" so that refilling the freon would cost less. Here in DC, with these 100 degree plus days and the humidity no less, the temperature coming out of the vents just isn't cold enough to keep up with the heat. I remember reading in a discussion a couple years ago about how one could actually LOWER the temperature of the air conditioning below the factory spec. Is this true and would anyone recommend doing it? Thanks for your replies in advance!