I remove the blower which is located near the windshield under the hood. I then removed the housing to the blower and took my 12v battery charger and connected it directly to the terminals on the blower motor to make sure that was the problem, which ran fine. I then concentrated my efforts on the in dash climate control system. After speaking with Phil at Mercedes Shop who informed me that the control systems screw up enough that there is a rebuild market, I purchased one from him. Removing and replacing the CCS is easy and took only about 15 minutes both ways; take out the ash tray, remove the 2 screws that hold the ashtray bracket, and everything above comes right out. The new unit worked like a charm.