Heater problem
 

I have recently purchased a 1993 190E with 133k. When I activate any of the controlds on the AC / Heater panel, an audible (and sometimes very loud) screeching sound eminates from behind the control panel. It is not the fan as the sound will fade away and return regardless of the fan setting. Further, this problem is worse during cold weather. Any ideas?

Porbably the aspirator motor for the ACC. Should be quiet with the ACC set to OFF. No idea where it is in a W124.

Sixto
95 S420
87 300SDL