Voltage is applied to both the air dryer and the moisture ejector heater through circuit breaker 9 when the ignition switch is in RUN. Both the air dryer and the moisture ejector heater are equipped with thermal switches that will close whenever the outside temperature reaches 4°C (40°F) or lower. With these thermal switches closed, the air dryer and moisture ejector heater circuit will be complete. The heating elements will turn ON to warm the components and keep the air in the system from freezing. The air dryer and moisture heater will remain ON until the ambient temperature rises above 4°C (40°F), or the ignition switch is moved out of the RUN position.