1999 Honda Accord Horizontal green light in AC button does

My son's 1999 Honda Accord AC is not cooling nor does the horizontal green light come on. Usually as we approach summer, I add freon to it and the AC cools fine for another year. I'm sure it has a small leak. But this is the first time I've noticed the green light not coming on. Would lack of freon keep the light from coming on or is this some other issue, possible a short? Should I go ahead and add freon to see what happens?