squelch a squealing vacuum servo?
 

My 126/ '91 350sd has an intermittent squealing noise coming from a little round plastic casing with a small fan spinning inside it that is connected to a vacuum line ( I think) on one end and a padded small metal housing with a powere supply on the other end. This is right below the glove box on the far right side. I can stop the squealing noise by stopping the fan from spinning in its plastic case. Now that I have finally found this %#@&**%! noise can someone tell me what it is, and how to fix it. I think it mingt have something to do w/ climate control and regulating the vent in the rear of the console as I noticed that when the heat is heat is flowing w/ fan on in the front, that cool air is coming out the rear vent? thanks:D

cabin temp sensor air pump
 

.... in want of the correct description.

AFAIK that little fan is in fact 'sucking' cabin air over a temp sensor fitted in the roof light (that's where it's in my 124).

The 'vacuum line' runs from the sensor in the roof ...

If it's noisy, try some Q20 or similar. Otherwise replace it.

any other takers ?