Heater Noise

Just wondering if anyone has experienced this same issue. I own a 97 Grand Prix GT. I bought it last Nov and ever since I've had it the heater seems to run abnormally loud (this could be normal) However, I can feel vibration in my steering wheel when the heater is on 4 or 5, high. It pushes out good hot air and the car runs great otherwise. Thanks for any input.

The only thing that I could think off is that there is a shutter on the AC housing on the car that touches the blower when the heater is on. Just look under the dash and check that all the pieces for the AC housing are snapped together correctly and there are no bends or anything. If all look normal then you should check the shuter that redirects cold/hot air to see if it sticks to something when open in heater mode