wow,ive been following this thread,and my 89 300ce is doing the same thing,no airflow comes from the center vent,even when its fully open,there is a noise coming from behind the glove box,i thought it maybe the blower motor,but when the blower motor is off i still hear it,when i switch the blower motor to high everything sounds normal.imgoing to check the black box,its vacum controlled,im wondering if this may be whats leading to my surging up and down idle,from a vacum leak,should the vacum unit be replaced?is this what most likley causes the weird noise behind glove box?