A repetitive clicking noise from behind the center area of the dash panel is usually caused by a broken stepper motor actuating arm. The actuating arm controls the direction of air flow in the climate control system. Disassembly of the center console will be required to access and change the broken arm with the updated, reinforced part.
Clicking Noise From Behind Center of Dash on Mercedes-Benz C350
Average mileage: 89,800 (89,800–89,800)
6 people reported this problem
2009 Mercedes-Benz C350 89,800 mi, Visitor
Noise pretty much stops if you turn off the fan if this is same problem I have.