power steering question.. already searched

[djsonic]

My car makes a humming noise when at idle, and gets a little bit louder when i turn the wheel. also sometimes it feel stiffer than others, and if im on snow and have the wheel at lock (i dont hink it matters which direction) and have the rear wheels spining (donuts or jsut trying to get out of a spot) tyhe power steering makes a loud whining, Ive had the car for about 7 months and it hasnt gotten any worse. my car is a 90, im assuming it has some kit on it because it has a blue power steering line? thanks for any help

sean p.s.i already searched the forum

[180fan]

have you checked the reservoir? it might be running low/leaking somewhere.