air volume and air distribution controls not working in mercedes c320
The most likely cause of this issue would be the climate control unit. The mode door actuator can prevent the different distribution zones from working properly. The blower motor or blower resistor can cause the fan speeds not to work properly.
However, if both of these functions quit working simultaneously, I would recommend having the control unit tested by a qualified professional. Consider YourMechanic, as one of our mobile technicians can come to your home or office to diagnose your A/C issue firsthand. If the control unit is not responsive, replacement of the control unit would be necessary to resolve the issue you are having.
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