A/C Problems

Hello , I am having some difficulty figuring out my AC problem.. Here it is.. whenI turn my AC on extremely hot air blows out.. it never gets cool.. also I have already charged the AC.. and have noticed that when the AC is on and the car is running. The Compressor seems to spin for about 3 secs and then it will go off.. I don't really know how long this should stay on. If anyone can help please give me your opinion..

I believe it is the compressor but I really dont know..

Thanks
Dragon Fly

the compressor may be junk but try changing the oriface tube(in line filter)and if that dont work try changing compressor