A/C Electronic Blower Regulator Control
WARNING: This page is about a different car, the 1997 Mercedes-Benz C280 and 1997 Mercedes-Benz C230. However, it is still accessible from the selected car via links, so may be relevant.
Connect socket box and 3-connector test cable to ACC push-button control unit right connector. See Figure. Turn ignition on. Connect voltmeter negative lead to socket box terminal No. 19 and voltmeter positive lead to terminal No. 1. Press fan button. At minimum fan speed, voltage should be greater than .7 volts. At maximum fan speed, voltage should be greater than .5 volts. If voltages are not to specification, check wiring.