Estimated, first of all you must ensure that the heaters work. It may happen that if the outer temperature (reflected in the cooling fluid of the motor) is not too low, the heaters do not share. The difficulty in starting and the white smoke of the escape is raw diesel (diesel) sign (without burning). The lighting of the light of heater does not guarantee that they work. To control if they work, it is enough to place a 12 volt pilot by placing a clamp in the feeding cable to heater and the other to mass and control that when giving heater the light turns on and control for how long it receives food. We keep in touch, good luck.