Defogger problems of the 2011 Chevrolet Suburban

The contact owns 2011 Chevrolet Suburban 1500. The contact stated that a mold and mildew odor was being emitted from the heating and cooling vents. The vehicle was taken to a dealer however, the mechanic could not diagnose the problem. The vehicle was not repaired. The manufacturer was made aware of the problem. The approximate failure mileage was 35,000.