[HayZee518]

check the control circuit via the furnace's schematic. if the control circuit is 24 volt then there has to be relays between the low voltage and 120 volt motors and/or solenoid. the blower undoubtedly is 120 volts, the humidifier belt drive motor is 120 volts also. the solenoid may be 24 I don't know without looking at the diagram but if its 120 volt then parallel this solenoid across the fan motors controller.