General Motors is recalling more than 9,000 MY 2009-2010 Chevrolet Express and GMC Savana vehicles because of problems with the defroster/defogger system. 

The recalled vehicles' heating, ventilation and air conditioning (HVAC) control knobs may fracture and spin on the control shaft. The driver could lose the ability to control the heating, cooling and ventilation for the vehicle. 

The driver's visibility could be compromised if this condition occurs and affects the defrost system, the National Highway Traffic Safety Administration said. 

To remedy the problem, dealers will replace all HVAC control knobs free of charge. The safety recall begins this month. 

Chevrolet can be reached at (800) 630-2438. GMC can be reached at (866) 996-9463.