Help I have a 98 XJ jeep cherokee 4L Limited and am getting a grinding or maybe air going through a pipe noise behind the dash in different spots when I get to about 55mph and gets worst the faster I go. My air con seems ok the heat and cold seems to work and I can change the air flow to where I wont to the floor or to my face. I have just replaced the motor in it but only just got it so I don't know if it did it before or not. Thanks anyone in advances for your help