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Home >> Subaru >> 2013 >> Outback Base, Standard Trans >> Repair and Diagnosis (Single Page) >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> HVAC System (Heater, Ventilator And A/C) - Mechanism & Function >> Heater System >> Heater And Cooling Unit >> Design Features For Each Air Flow Mode
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Design Features For Each Air Flow Mode

  1. Ventilation (FACE) mode
    • The passage leading air from the evaporator to the ventilation duct is made straight to reduce air flow resistance.
    • When the air temperature is necessary to be adjusted, heated air is blown at right angles against the flow of cool air from the evaporator. This allows the airs to mix thoroughly.
    Fig 1: Air Flow Operation Diagram (Ventilation Mode)
    G08260420Courtesy of SUBARU OF AMERICA, INC.
  2. Foot/face (BILEVEL) mode
    • The air that has flown through the evaporator is divided into two directions. Part of this air flows through the heater core and becomes warm air. The rest of the air goes to the outlet as cool air, however, this is mixed with the warm air from the heater core. The mixed air then flows to the ventilation and heater ducts.
    Fig 2: Air Flow Operation Diagram (Foot/Face Mode)
    G08260421Courtesy of SUBARU OF AMERICA, INC.
  3. Heating (FOOT) mode
    • The air that has flown through the evaporator is heated at the heater core and then flows to the heater ducts.
    • To defog the windshield, the defroster door is slightly open and warm air is also sent to the defroster (DEF) duct.
    • The side ventilation grills ventilate air always.
    Fig 3: Air Flow Operation Diagram (Heating Mode)
    G08260422Courtesy of SUBARU OF AMERICA, INC.
  4. Defroster (DEF) mode
    • Air passages are designed in such a way that air flow resistance is minimized and defrosting performance is maximized.
    • The air passages toward the defroster (DEF) outlet is long enough to ensure a same airflow rate at all defroster outlets.
    • The side ventilation grills ventilate air always.
    Fig 4: Air Flow Operation Diagram (Defroster Mode)
    G08260423Courtesy of SUBARU OF AMERICA, INC.
  5. Defroster (DEF)/Heating (FOOT) mode
    • The air from the evaporator flows through the heater core and the warmed air flows to the defroster (DEF) duct and foot duct to defog the windshield while sending warm air to the legs.
    • The air directed to the defroster duct flows out from the front and side defroster ducts to defog the windows.
    • The side ventilation grills ventilate air always.
Fig 5: Air Flow Operation Diagram (Defroster/Heating Mode)
G08260424Courtesy of SUBARU OF AMERICA, INC.
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