2009 Aveo LT. AutoTrans , Rattle/Rumble Noise when using defroster setting on rotary switch, 103K miles.

This just started after a cold snap.

Does not make this Rattle/Rumble when using the other settings on the rotary switch.

Is there a ventilation " Solenoid / Redirector valve" or "Air Door Actuator" that could be bad or the motor.

Any suggestions, others have this issue ?