Change Power steering fluid
 

My daughters 99 Alero had a real noisy P/S whine. I checked the fluid and it was burnt!. I used a turkey baster and sucked out the reservoir. There is a spot towards the back of the res that is deeper. Then ran it a bit until it filled up again then sucked it out. I then filled it with clean fluid and did the whole thing again. Now it's nice and quiet. Not a total flush, but, it was easy and worked.