A fan apparatus is disclosed which includes a fan coupled to a drive mechanism via a viscous clutch. The viscous clutch includes a drive chamber containing a hydraulic fluid with an amount of hydraulic fluid in the drive chamber being related to a torque transmitted from said drive mechanism to the fan; a valve coupled to the drive chamber controlling flow of hydraulic fluid into the drive chamber; a bimetallic strip coupled to the valve; and a heating element coupled to the viscous clutch close to the bimetallic strip. The bimetallic strip is located in a position open to ambient air.