- Heating principle (HEATER CORE): When the hot coolant generated from ENGINE passes through the heater core. he principle that the air generated by the blower is heated and the room is heated.
- Cooling Principle (EVAP. CORE): Low temperature low pressure liquid refrigerant from EXPANSION VALVE is vaporized. The principle that the ventilation heat coming out is blown into the room through FAN to cool the room indoors.