clutch goes on and off on ac compressor on 2001 ford taurus

System is low on charge, probably has a slow leak.

An "01 is an old car. Things have to be maintained to work properly. I agree that the AC refrigerant is low and needs a recharge. But for safety sake, have an AC tech go over the AC system to make sure everything is in proper condition. A few bucks spent now can save you a huge expense in the long run.

my gauge said refrigerant was full!!! Its a brand new compressor and at first it was blowing cold air 3 days later its blowing warm air so we looked and seen the clutch would spend for few seconds then stop then spin etc...

Still sounds like a leak, what do the pressures show? It is possible the cycling switch went bad but I still think you have a leak.