Scheme 77
- The Impreza's HVAC system uses an integral air conditioning unit with thin-wall, high-performance heater core at the front and evaporator core at the rear. Being compact in size, this unit enables providing sufficient front passenger's legroom while ensuring a high air-distribution efficiency by minimizing air flow resistance in all air passages. Overall, the system can create comfortable interior air conditions quietly and in all seasons by its excellent heating, cooling, ventilating, and defrosting performances.
- There are three ventilation grilles in the dashboard; a trapezoidal grille at the center and round grilles at both sides. The side grilles are rotatable for air flow direction adjustments.
- To ensure adequate ventilation, large-size air outlets are provided behind the side portions of the rear bumper where high-level vacuums are generated during driving.
Scheme 78
Scheme 79
CONTROL PANEL
- The HVAC control panel is incorporated into the center panel.
- A rear window defogger switch is located in the control panel.
Scheme 80
Scheme 81
Scheme 82
- The control panel uses three large-diameter, dial type switches for easy operation and good visual recognition. Air outlet control dial: This switch allows selecting any of the five air flow modes. Fan speed control dial: This switch allows turning on/off the blower and selecting any of the four blower speeds. Temperature control dial: This switch allows adjusting the temperature of air delivered through ventilators steplessly. Rear window defogger switch: This switch activates the rear defogger. When the switch is left on, a timer keeps the defogger activated for 15 minutes and then turns it off automatically. FRESH/RECIRC lever: This lever allows selecting either cabin-air-recirculation or fresh-air-introduction. Air conditioning switch: This switch turns on or off the air conditioning compressor.
Scheme 83
- Having an evaporator core at the front and a heater core at the rear, this single unit combines both heating and cooling functions.
- The heater and cooling unit incorporates doors for creating different air flow modes and a door for mixing heated air and outside air.
- The air flow mode switching doors and air mixing door are moved by cables through corresponding linkages.
Scheme 84
Scheme 85
Scheme 86
Scheme 87
Scheme 88
- Ventilation (VENT) mode The passage leading air from the evaporator to the ventilation outlet (VENT) 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.
- Foot/face (BI-LEVEL) mode Warm and cool air flows are created by structural means, namely, by forming sealing surface for air toward leg area on the heated air passage side and that for air toward the ventilation outlet (VENT) on the cooled air passage side. To prevent an excessive difference in the temperature between the two air flows, a bypass passage is provided to allow part of heated air to flow toward the ventilation (VENT) outlet.
- Heating (HEAT) mode Warm and cool air flows are created by structural means, namely, by forming sealing surface for air toward leg area on the heated air passage side and that for air toward the defroster (DEF) outlet on the cooled air passage side. To prevent an excessive difference in the temperature between the two air flows, a bypass passage is provided to allow part of heated air to flow toward the ventilation (VENT) outlet. To maintain the passage toward the defroster (DEF) outlet even during the heating mode operation, the door of the passage toward leg area is fully opened to the make the passage also serve as a passage toward the defroster (DEF) outlet.
- 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.
Scheme 89
- The blower unit uses a low-noise-type motor.
Scheme 90
- The ventilation duct and defroster duct are located behind the instrument panel. Both the ducts have been modified in the shape to reduce air flow resistance.
- Defrosting air flow is divided at the center, so that air can flow out evenly through a wide center defroster as well as right and left side defrosters.
GENERAL
The air conditioning system has a newly-developed subcooling condenser for improved heat-exchange efficiency.
As with the previous model's air conditioning system, the refrigerant employed is the chlorine-free HFC-134a (R134a), which does not contribute to ozone-layer damage.
A simple system structure is realized by incorporation of the receiver dryer into the condenser.
Scheme 91
COMPRESSOR
The rotary type compressor consists of an integrally formed rotor and shaft, five vanes, and a cylinder.
As the rotor turns, the movable vanes that are fitted in the rotor slide over the wall of the oval-shaped cylinder while drawing, compressing, and discharging refrigerant gas.
The compressor shell has at its rear and an oil separator. High-pressure refrigerant gas having entered this chamber is separated from the oil it contains before flowing out through the compressor's delivery port.
There is a check valve in the front housing to avoid reverse rotation of the compressor which would otherwise occur when the compressor is stopped.
Scheme 92
PRESSURE RELIEF VALVE
This valve opens if the pressure of the high-pressure refrigerant gas rises to a dangerously high level to release part of refrigerant into the atmosphere, thus protecting the compressor. The valve is designed to limit the amount of released gas to the necessary minimum.
- Valve opening pressure: 3.72 MPa (38 kgf/cm 2 )
- Valve closing pressure: 1.8 MPa (17.5 kgf/cm 2 )
Scheme 93
Scheme 94
COOLING UNIT
The heater unit and cooling unit are integrated into a single "heater and cooling unit".
The cooling section components of this unit include an evaporator, expansion valve, and case.
Scheme 95
EVAPORATOR
The evaporator is a laminated type.
When a low-pressure, low-temperature refrigerant is sprayed by the expansion valve into the evaporator, it evaporates and cools the evaporator surfaces.
The cabin air is drawn by the blower and cooled down as it flows over the evaporator. The cooled air then flows passing through the heater unit and delivered into the cabin through versions outlets.
Scheme 96
EXPANSION VALVE
The expansion valve regulates the flow of refrigerant such that heat exchange takes place optimally.
The expansion valve performs two functions; it sprays the high-pressure refrigerant from the condenser using a throttle valve, and it regulates the amount of the spray by changing opening of the throttle valve.
The expansion valve consists of such main components as a heat sensing cylinder, diaphragm, ball valve, spring, and adjusting screw.
Scheme 97
The heat (temperature) sensing cylinder is held in contact with the evaporator outlet pipe so that a pressure corresponding to the sensed temperature may be applied to the chamber above the diaphragm. There is a pressure equalizing hole which communicates with the chamber below the diaphragm to transmit changes in the refrigerant pressure to the chamber. The ball valve is linked with the diaphragm and moves according to changes in the balance between the force applied to the diaphragm and the tension of the spring.
CONDENSER
The condenser used in the Impreza's air conditioning system is the newly developed "subcooling condenser" that integrates a multi-flow type condenser and a modulator (gas-liquid separator) into a single unit. The condenser has a high heat-exchange efficiency.
Scheme 98
SUBCOOLING CONDENSER
The new subcooling condenser has a subcooling section where part of the refrigerant that remains in gas form is cooled and reduced into liquid form. This enables almost 100% of the refrigerant to be re-liquefied.
Scheme 99
PRESSURE SWITCH
The pressure switch is a high-pressure side component of the refrigeration cycle (cooling cycle). It consists of a diaphragm that receives refrigerant gas pressure, a snap plate, a rod, and contacts that open both when the gas pressure is too low and when it is too high.
The pressure switch plays the following roles
Scheme 100
Scheme 101
- Prevents "no-gas" operation due to leakage (when gas pressure is too low)
- Protects the cooling system against abnormally high refrigerant pressure (when gas pressure is too high)
