My ac kicks on sometimes then shuts off. I hear it kicking on but why no ac? on 1999 Pontiac Bonneville

This problem just started. When you go to turn on the ac switch, you hear it kicking on, but no ac blower air comes on. However, when the car makes up it's mind while driving, the ac comes on with cool air.

Asked by for the 1999 Pontiac Bonneville