Overhead Control Panel (OCP) (N70)
Refer to: WIS 83.40 Automatic Climate Control (ACC) or Heating Ventilation and Air Conditioning (HVAC)
DIY Procedures - Overhead Control Panel (OCP) (N70)
DIY Dismantle and Repair - W220 2005 S500 OCP
Excellent article by BenzWorld Member jwells at Post #8:
http://www.benzworld.org/forums/w220-s-class/1460424-need-help-c-diag.html