squeal from multiport vac. switch behind vent
 

1992 190e. Im looking for some advice on a persistant underdash squeal beside the glovebox just below the vent. It has the sound of a dry blower motor bearing but it is not the blower motor in this case. Ive opened up the glove box and found a climate control mulitport vacuum unit to the right behind the vent with several green and red vacuum lines in it along with a few electrical wires. This black box is about six or 7 inches side to side and strapped in with a factory zip-tie. With my hand on this box I can feel a slight vibration that accompanies the squeal as I turn the key to accessory (no engine running thus no engine vacuum generated at this point). As I switch the key on and off its almost like im hearing a tiny motor in there spooling up and making the noise. What am I dealing with here? Is there a pump or some kind of motor connected with this module? What do I call this part if I want to order a new one?? thanks so much.