Take a hand baster and pump out as much fluid as you can from the fill cap to the power steering fluid. Then replace the fluid with some +4 transmission fluid. It cured the exact problem we had last week with our 04 mini-van. I was surprised that this simple procedure got rid of the noise which sounded like a broken pump.
2004 Town & Country Limited, Michlin HydroEdge, added OEM Rear Sway Bar, German OEM Headlights with Hella H7+30 and H9 bulbs, Centric Rotors, Akabono Ceramic Pads, front and rear, rear hitch.
2001 PT Cruiser Limited automatic, Goodyear TripleTread rear, Goodyear Eagle ResponseEdge front, performance sway bar bushings and front links, 9011 and 9012 bulbs, front tower bar, Centric Rotors, Akabono Ceramic Pads, front only, Champion dual plat plugs, Mopar performance plug wires.