If the noise is a squeal then belt is slipping, but it could be either a worn belt, or a bad pump. If it is a groaning noise, then again, it could be a bad pump, or a bad steering rack, or it could just be low fluid.
The only way to know for certain is to have someone look at it.
Nobody can diagnose the car without seeing it in person. First check the power steering fluid with the car off, make sure it's at the proper level. If it is, take notice if the noise is coming from around the pump, if so replace the pump with a delco power steering pump and dont forget to have the shop flush and bleed the system as well.