Abstract: A heater for heating an enclosure associated with a motor vehicle having a liquid coolant system for storage of materials that may damaged by freezing temperatures, such as a truck utility box. The heater comprises an enclosure with an aperture in communication with the enclosure, a heat exchange means for transferring heat from coolant from the cooling system of the vehicle flowing through the heat exchange means to the air flowing adjacent to the heat exchange means, and a electrical blower means for forcing air through the heat exchange means and out of the enclosure into the enclosure through the aperture. The blower means has an electrical control means for controlling its function by a driver of the vehicle.