Warm Push-Button Indicator Light
WARNING: This page is about a different car, the 1999 Mercedes-Benz SL500 and 1998 Mercedes-Benz SL500. However, it is still accessible from the selected car via links, so may be relevant.
Connect socket box to A/C push-button control unit left connector. Connect voltmeter negative lead to socket box terminal No. 19. Connect voltmeter positive lead to socket box terminal No. 6. Turn ignition on. Voltage should be more than 3.5 volts and Red indicator light should be on. If voltage is not as specified, check wiring. If wiring is okay, replace center and side air outlet flap control unit.