The blower on my '00 e320 works only intermittently. Actually when it is cold outside (low 40s and below) the blower will not blow at all, but you can feel heat it you put your hand down by the vents. Seems to work most of the time in warm weather, but not always. All controls work fine, and you can hear the dampers moving when selecting controls.

Need a new voltage regulator for the blower motor.
May also need the blower motor replaced if it is the one that needs the updated version. Check with the m.b. dealer for the proper part number .