2000 Pontiac Sunfire noise coming from altenator area

I just a 2000 sunfire gt, 2.4 twin cam a month ago, I had the altenator and belt replaced and all four brakes replaced. After going to the car wash a week ago (I didn't wash the engine just the outside of the car) my car makes a whirling/squill noise coming from the altenator area. It only makes the noise travelling under 30km/h when I step on the gas and speed up to 50km/h the noise goes away. I'm not stepping on the brakes. I put belt dressing spray on the belt. Car runs fine. So far the only thing I can think of to get rid of the noise is just turn the stereo up