The instant invention pertains to a road vehicle's axial flow cooling fan which normally draws cooling air from in front of the vehicle and blows it into the engine bay. The instant invention includes a control circuit for the fan motor that provides variable speed and bi-directional, or reverse and normal, fan operation. Reverse fan operation blows air from the engine bay through the radiator and out the front of the vehicle, and normal fan operation blows into the engine bay. Two input sensors feed the control circuit, one for road speed of the vehicle and other for engine temperature. When the engine is below its operating temperature and the vehicle is moving, the fan is made to blows in reverse at a speed proportional to road speed so as to block cold ram air from entering and blasting onto a warming engine. This speeds engine warm-up to reduce emissions, improve fuel economy, and speed windshield defogging. The fan may also be made to blow in reverse when the engine is cold and the vehicle is stopped, in order that exhaust-heated air from the exhaust manifold behind the engine, may be drawn forward over the engine block to speed its warming. When the engine is above its operating temperature and the vehicle is idling or moving slowly, as in traffic, then the control circuit causes the fan to again blow in reverse cooling both the radiator and the engine bay components and preventing hot, noxious fumes from vehicles in front from being drawn into the vehicle. Blowing in reverse in traffic conditions also eliminates hot air looping back to the front of the car and drawn in through the radiator. As vehicle speed increases, the fan is made to revert to normal operation augmenting ram air flow through the radiator.