AIR CONDITIONING SYSTEM DETAILS


  1. SYSTEM CONTROL


    1. The air conditioning system uses the following controls.

      Control Outline
      Neural Network Control This control is capable of effecting complex control by artificially simulating the information processing method of the nervous system of living organisms in order to establish a complex input / output relationship that is similar to a human brain.
      Automatic Recirculation Control Automatically changes the air inlet mode to recirculate mode when the outside temperature exceeds 75°F (23.6°C) with the A/C on.
      Manual Control The air conditioning amplifier assembly controls the damper positions (air inlet control servo motor, air mix control servo motor and mode control servo motor) and blower speed in accordance with the positions of the switches (temperature control switch, blower switch, mode control switch and inlet control switch).
      Outlet Air Temperature Control Based on the temperature set at the temperature control switch, the neural network control calculates the outlet air temperature based on the input signals from various sensors.
      Left and Right Independent Control The temperature setting for the driver and front passenger is controlled independently in order to provide a separate vehicle interior temperature for the right and left sides of the vehicle. Thus, air conditioning control that accommodates occupant preferences has been realized.
      Blower Control Controls the blower motor in accordance with the airflow volume that has been calculated by neural network control based on the input signals from various sensors.
      Air Outlet Control Automatically switches the air outlets in accordance with the outlet mode that has been calculated by neural network control based on the input signals from various sensors.
      In accordance with the engine coolant temperature, outside air temperature, amount of sunlight, required blower, outlet temperature, and vehicle speed conditions, this control automatically switches the blower outlet to FOOT/DEF mode to prevent the windows from becoming fogged when the outside air temperature is low.
      Air Inlet Control Automatically controls the air inlet control damper to achieve the calculated outlet air temperature that is required.
      Electric Inverter Compressor Control Compressor Speed Control The air conditioning amplifier assembly calculates the target speed of the compressor based on the target evaporator temperature (which is calculated by the temperature control switch, air conditioning thermistor assembly (humidity), cooler (room temp. sensor) thermistor, outside temperature sensor (thermistor assembly), and solar sensor (automatic light control sensor)) and the actual evaporator temperature that is detected by the evaporator temperature sensor (No. 1 cooler thermistor) in order to control the compressor speed.
      The air conditioning amplifier assembly calculates the target evaporator temperature, which includes corrections based on the temperature control switch, air conditioning thermistor assembly (humidity), cooler (room temp. sensor) thermistor, outside temperature sensor (thermistor assembly), solar sensor (automatic light control sensor), and evaporator temperature sensor (No. 1 cooler thermistor). Accordingly, the air conditioning amplifier assembly controls the compressor speed to an extent that would not inhibit the proper cooling performance or defogging performance.
      Turns the air conditioning ON automatically when the AUTO button is pressed when the blower is ON and the air conditioning is OFF.
      Decreases the compressor speed in order to ensure quietness when the vehicle is stopped or the engine is off.
      Refrigerant Shortage Detection Control When the air conditioning is operating and the engine coolant temperature is above a specified value, the air conditioning amplifier assembly calculates the amount of refrigerant based on signals from the air conditioning pressure sensor, evaporator temperature sensor (No. 1 cooler thermistor) and outside temperature sensor (thermistor assembly).
      PTC Heater Control

      When the hybrid system is operating (READY), and the blower with fan motor sub-assembly is turned on, the air conditioning amplifier assembly turns on the quick heater assembly if the conditions listed below are met.

      - Engine coolant temperature is below specified temperature.

      - Outside temperature is below specified temperature.

      - Tentative air mix damper opening angle is above the specified value (MAX HOT).
      Electric Engine Water Pump Control The air conditioning amplifier assembly calculates the flow rate value required for the electric engine water pump assembly in accordance with the engine coolant temperature and air mix damper opening degree and sends it to the ECM.
      ECO Mode Control When the ECO mode switch (eco switch assembly) is turned on, the air conditioning amplifier assembly limits the air conditioning system performance.
      Defroster Control Defroster control logic is used to improve defroster performance.
      Rear Window Defogger Control When the rear defogger switch is pushed, the system is activated to keep the defogger heater on for approx. 15 minutes.
      Diagnosis A Diagnostic Trouble Code (DTC) is stored in memory when the air conditioning amplifier assembly detects a problem with the air conditioning system.

    2. Neural Network Control


      1. Previously, in automatic air conditioning systems without neural network control, the air conditioning amplifier assembly determined the required outlet air temperature and blower air volume in accordance with the calculation formula that has been obtained based on information received from the sensors. However, because the senses of a person are rather complex, a given temperature is sensed differently, depending on the environment in which the person is situated. For example, a given amount of solar radiation can feel comfortably warm in a cold climate, or extremely uncomfortable in a hot climate. Therefore, as a technique for performing a higher level of control, a neural network has been adopted in the automatic air conditioning system. With this technique, the data that has been collected under varying environmental conditions is stored in the air conditioning amplifier assembly. The air conditioning amplifier assembly can then perform control in a way that provides enhanced air conditioning comfort.

      2. The neural network control consists of neurons in the input layer, intermediate layer and output layer. The input layer neurons process the input data of the outside temperature, the amount of sunlight, and the room temperature based on the outputs of the switches and sensors, and output them to the intermediate layer neurons. Based on this data, the intermediate layer neurons adjust the strength of the links among the neurons. The sum of these is then calculated by the output layer neurons in the form of the required outlet temperature, solar correction, target airflow volume and outlet mode control volume. Accordingly, the air conditioning amplifier assembly controls the servo motors and blower motor in accordance with the control volumes that have been calculated by the neural network control.

        A01HS8HE02

    3. PTC Heater Control


      1. The output of the quick heater assembly is controlled by the air conditioning amplifier assembly in accordance with the engine coolant temperature, engine speed, air mix setting, and electrical load (generator assembly power ratio).

        A01HS7AE01

    4. ECO Mode Control


      1. During ECO mode control, the air conditioning amplifier assembly restricts the air conditioning system performance under specified conditions, thus improving fuel economy.

      2. ECO mode control is activated when the ECO mode switch (eco switch assembly) is pushed, and then restricts the air conditioning system performance as described below.

        Control Outline
        Inside/outside Air Switch Control Automatically switches the air inlet port to recirculation mode when the outside air temperature is equal to or higher than a predetermined temperature and reduces the power consumption.
        Blower Level Control Sets the blower level in AUTO mode lower than normal, and suppresses the power consumption.
        PTC Heater Control Suppresses the power consumption.
        Heating Restriction Control Changes the air outlet temperature by entering ECO mode during heating and increases the amount of engine-off time when the drive mode is in ECO, thus improving fuel economy.
        Compressor Speed Restriction Control Restricts the maximum compressor speed during cooling and reduces the power consumption.

  2. CONSTRUCTION


    1. Air Conditioning Control Assembly


      1. A push-button and dial type air conditioning control assembly is used.

      2. The air conditioning control assembly uses a Liquid Crystal Display (LCD).

        A01HS6T

    2. Air Conditioning Radiator Assembly


      1. The air conditioning radiator assembly consists of the evaporator, heater radiator unit sub-assembly, servo motors, evaporator temperature sensor (No. 1 cooler thermistor) and blower with fan motor sub-assembly.

      2. A semi-center location air conditioning radiator assembly, in which the evaporator and heater radiator unit sub-assembly are placed in the vehicle's longitudinal direction. As a result, the air conditioning radiator assembly has been made compact and lightweight.

        A01HS1BE01
        Text in Illustration
        *1 Evaporator *2 Heater Radiator Unit Sub-assembly
        *a Side View *b Top View
        A01HS1C Front - -

    3. Evaporator


      1. A Revolutionary super-Slim structure (RS) type evaporator is used.

      2. Placing the tanks at the top and the bottom of the evaporator and adopting a micropore tube construction has provided the following benefits:


        • The heat exchanging efficiency has been improved.

        • The temperature distribution has been made more uniform.

        • The evaporator has been made thinner.

        A01HS8FE02
        Text in Illustration
        *1 Tank *2 Micropore Tube
        *3 Cooling Fin - -

    4. Evaporator Temperature Sensor (No. 1 Cooler thermistor)


      1. The evaporator temperature sensor (No. 1 cooler thermistor) detects the temperature of the cooled air immediately past the evaporator in the form of resistance changes, and outputs this data to the air conditioning amplifier assembly.

    5. Heater Radiator Unit Sub-assembly


      1. The compact, lightweight and highly efficient Straight Flow Aluminum (SFA)-II type heater radiator unit sub-assembly is used for the air conditioning system.

        A01HRVME02
        Text in Illustration
        *1 Tank - -

    6. Quick Heater Assembly


      1. The quick heater assembly consists of a PTC element, an aluminum fin, and a brass plate. When current is applied to the PTC element, it generates heat to warm the air that passes through the unit.

        A01HS0VE01
        Text in Illustration
        *1 PTC Heater *2 Aluminum Fin
        *3 Brass Plate *4 PTC Element

    7. Blower with Fan Motor Sub-assembly


      1. The blower with fan motor sub-assembly has a built-in blower controller which is controlled by the air conditioning amplifier assembly.

    8. Air Conditioning Harness Assembly


      1. An air conditioning harness assembly is used in the wire harness connection that connects the servo motor from the air conditioning amplifier assembly.

        A01HRU6E01
        Text in Illustration
        *1 Bus Connector *2 Air Conditioning Harness Assembly
        *a To Air Conditioning Amplifier Assembly *b To Evaporator Temperature Sensor (No. 1 Cooler Thermistor)

      2. The air conditioning harness assembly has a built-in driver IC with a position detection function that communicates with each servo motor connector and actuates the servo motor. This enables bus communication for the servo motor wire harness with a more lightweight construction and a reduced number of wires.

        A01HRXXE03
        Text in Illustration
        *A Models with Bus Connector *B Models without Bus Connector
        *1 Air Conditioning Amplifier Assembly *2 Bus Connector
        *3 Communication Driver IC *4 Servo Motor
        *5 Communication IC *6 CPU
        *7 Driver IC - -

    9. Servo Motor


      1. The pulse pattern type servo motor consists of a printed-circuit board and a servo motor. The printed-circuit board has 3 contact points, and can transmit 2 on-off signals to the air conditioning amplifier assembly based on the difference in the pulse phases. The bus connector can detect damper position and direction of movement with this signal.

        A01HS5OE05

    10. Clean Air Filter


      1. A pollen removal type air refiner element is used to remove dust, pollen and other micron particles from air entering from outside the vehicle to provide a comfortable cabin of clean air. The air refiner element is installed in the upper section of the blower with fan motor assembly.

        A01HRVDE01
        Text in Illustration
        *1 Air Refiner Element *2 Pollen
        *3 Micron Particle - -
        *a Image of Air Refiner Element *b Large Foreign Object Filter Layer
        *c Electret Layer - -

    11. Cooler Condenser Assembly


      1. The cooler condenser assembly consists of 2 cooling portions: a condensing portion and a super-cooling portion. These portions are integrated with a gas-liquid separator (modulator). This cooler condenser assembly uses a sub-cool cycle that offers excellent heat-exchange performance.

      2. In the sub-cool cycle, after the refrigerant passes through the condensing portion of the condenser, both the liquid refrigerant and the gaseous refrigerant that could not be liquefied are cooled again in the super-cooling portion. Thus, the refrigerant is sent to the evaporator in an almost completely liquefied state.

      3. The desiccant and filter at the bottom of the modulator remove moisture and debris from the refrigerant.

        A01HRTBE01
        Text in Illustration
        *1 Gaseous Refrigerant *2 Condensing Portion
        *3 Modulator *4 Desiccant
        *5 Filter *6 Super-cooling Portion
        *7 Liquid Refrigerant - -

        Tech Tips

        The point at which the air bubbles disappear in the refrigerant of the sub-cool cycle is lower than the proper amount of refrigerant with which the system must be filled. Therefore, if the system is recharged with refrigerant based on the point at which the air bubbles disappear, the amount of refrigerant would be insufficient. As a result, the cooling performance of the system would be affected. Overcharging the system with refrigerant will also lead to reduced performance. For the proper method of verifying the amount of refrigerant and for instructions on how to recharge the system with refrigerant, refer to the Repair Manual.

        A01HRTOE01

    12. Compressor with Motor Assembly


      1. Along with the installation of the hybrid system, an ES27 type electric inverter compressor that is driven by a motor is used. The basic construction and operation of this compressor is the same as an ordinary scroll compressor, except that it is driven by an electric motor.

      2. The A/C inverter is integrated with the compressor.

      3. The electric motor is actuated by 3-phase alternating current created from the direct current (244.8 V) supplied to the A/C inverter. As a result, the air conditioning system is actuated without depending on the operation of the engine, thus realizing a comfortable air conditioning system and low fuel consumption.

      4. Due to the use of an electric inverter compressor, the compressor speed can be controlled at the required speed calculated by the air conditioning amplifier assembly. Thus, the cooling and dehumidification performance and power consumption have been optimized.

      5. Low-moisture permeation hoses are used for the suction and discharge hoses at the compressor in order to minimize the entry of moisture into the refrigeration cycle.

      6. The compressor is supplied with high-voltage direct current, and it uses high-voltage alternating current internally. If an open or short circuit occurs in the compressor, the power management control ECU will cut off the A/C inverter circuit.

        A01HRXUE01
        Text in Illustration
        *1 A/C Inverter *2 Discharge Hose Port
        *3 Suction Hose Port - -

      7. The electric inverter compressor consists of a spirally wound fixed scroll and rotating scroll that form a pair, a brushless motor, an oil separator, a motor shaft and A/C inverter.

      8. The fixed scroll is integrated with the housing. Because the rotation of the shaft causes the rotating scroll to revolve while maintaining the same posture, the volume of the space that is partitioned by both scrolls varies to perform the suction, compression, and the discharge of the refrigerant gas.

      9. Locating the suction port directly above the scrolls enables direct suction, thus realizing improved suction efficiency.

      10. Containing a built-in oil separator, this compressor is able to separate the compressor oil that is intermixed with the refrigerant and circulates in the refrigeration cycle, thus realizing a reduction in the oil circulation rate.

      11. This inverter converts the HV battery nominal voltage of DC 244.8 V into AC and supplies power to operate the compressor.

        A01HS9IE08
        Text in Illustration
        *1 A/C Inverter *2 Discharge Port
        *3 Motor Shaft *4 Rotating Scroll
        *5 Fixed Scroll *6 Oil Separator
        *7 Brushless Motor *8 Electric Inverter Compressor
        *9 HV Battery *10 Current Sensor
        *11 Power Supply Circuit *12 Gate Drive Circuit
        *13 Temperature Sensor *14 Voltage Sensor
        *15 Power Management Control ECU *16 Input/Output Interface
        *17 CPU *18 System Protection Control Circuit
        *a From Battery - -

        Note

        In order ensure proper insulation of the internal high-voltage portion of the compressor and the compressor housing, this model has adopted compressor oil (ND11) with a high level of insulation performance. Therefore, never use compressor oil other than the ND11 type compressor oil or its equivalent.

    13. Air Conditioning Thermistor Assembly (Humidity)


      1. An air conditioning thermistor assembly (humidity), in which the glass temperature sensor, glass surroundings temperature sensor and glass humidity sensor are integrated, is used.

      2. The glass temperature sensor detects the surface temperature of the windshield using the built-in thermistor attached to the back of the sensor board, and outputs the signal to the air conditioning amplifier assembly.

      3. The glass surroundings temperature sensor detects the air temperature near the windshield using the built-in thermistor, and outputs the signal to the air conditioning amplifier assembly.

      4. The glass humidity sensor converts a change in the electrostatic capacity between the electrodes by allowing the humidity-sensing film to adsorb and desorb moisture in the cabin, and outputs the signal to the air conditioning amplifier assembly.

    14. Cooler (Room Temp. Sensor) Thermistor


      1. The cooler (room temp. sensor) thermistor detects the room temperature based on changes in the resistance of its built-in thermistor. This signal is used by the air conditioning amplifier assembly.

    15. Outside Temperature Sensor (Thermistor Assembly)


      1. The outside temperature sensor (thermistor assembly) detects the outside temperature based on changes in the resistance of its built-in thermistor. This signal is used by the air conditioning amplifier assembly.

    16. Solar Sensor (Automatic Light Control Sensor)


      1. The solar sensor (automatic light control sensor) consists of a photo diode, 2 amplifier circuits and a frequency conversion circuit.

      2. The solar sensor (automatic light control sensor) detects (in the form of changes in the current that flows through the built-in photo diode) the changes in the amount of sunlight from its left and right sides (2 directions) and outputs these sunlight strength signals to the air conditioning amplifier assembly for the automatic air conditioning control.

        A01HRUQE09

  3. OPERATION


    1. Mode Position and Door Operation


      1. Air Conditioning Unit

        A01HS3NE02
        Control Damper Operation Position Door Position Operation
        Air Inlet Control Damper FRESH A Allows fresh air to enter.
        RECIRCULATION B Causes internal air to recirculate.
        Air Mix Control Damper MAX COLD to MAX HOT Temperature Setting

        C - D - E

        (C' - D' - E')

        T - U - V

        		 Varies the mixture ratio of the warm air and the cool air in order to regulate the temperature continuously between hot and cold.
        Mode Control Damper A01HS0Z FACE I, K, M, O, S, W Air blows out of the front and rear center registers, and side registers.
        A01HRUH BI-LEVEL I, K, N, O, R, X Air blows out of the front and rear center registers, side register and front and rear footwell registers ducts.
        A01HS2Y FOOT H, J, L, P, Q, X Air blows out of the front and rear footwell register duct, and side registers. In addition, air blows out slightly from the center defroster and side defrosters.
        A01HRY7 FOOT/DEF G, J, L, P, Q, X Defrosts the windshield through the center defroster, side defrosters, side registers, and rear center register, while air is also blown out from the front and rear footwell register ducts.
        A01HRVF DEF F, J, L, P, S, Y Defrosts the windshield through the center defroster, side defroster, and side registers.

    2. Air Outlets and Airflow Volume

      A01HS1LE03
      MODE Selection Register Footwell Defroster
      AUTO Manual CTR SIDE RR CTR RR
      A B C D E F

      FACE

      A01HS0Z       		A01HS6R A01HS6R A01HRWC A01HRWC A01HRWC A01HS0I A01HS0I A01HS0I

      BI-LEVEL

      A01HRUH       		A01HS6R A01HS6R A01HRWM A01HRWM A01HRWM A01HS54 A01HS54 A01HS0I

      FOOT-F*1

      A01HS2Y       		A01HS6R A01HS0I A01HS0I A01HS54 A01HS54 A01HRWM A01HS54 A01HRWD

      FOOT-R*2

      A01HS2Y       		A01HS6R A01HS6R A01HS0I A01HS54 A01HS54 A01HRWM A01HRWM A01HRWD

      FOOT-D*3

      A01HS2Y       		A01HS6R A01HS0I A01HS0I A01HS54 A01HS54 A01HS54 A01HS54 A01HS54

      FOOT/DEF

      A01HRY7       		A01HS6R A01HS6R A01HS0I A01HS54 A01HS54 A01HRWM A01HRWM A01HRWM

      DEF

      A01HRVF       		A01HS6R A01HS6R A01HS0I A01HS54 A01HS0I A01HS0I A01HS0I A01HRUD

      • *1: Regular foot mode

      • *2: Foot mode with large airflow volume from footwell rear ducts

      • *3: Foot mode with large airflow volume from defrosters

      • The size of each circle ○ indicates the ratio of airflow volume.

    3. Cooler Compressor Operation


      1. Suction Operation

        As the capacity of the compression chamber, which is created between the rotating scroll and the fixed scroll increases in accordance with the revolution of the rotating scroll, refrigerant gas is drawn in from the intake port.

      2. Compression Operation

        From the state at which the suction process has been completed, as the revolution of the rotating scroll advances further, the capacity of the compression chamber decreases gradually. Consequently, the refrigerant gas that has been drawn in becomes compressed gradually and is sent to the center of the fixed scroll. The compression of the refrigerant gas is completed when the rotating scroll completes approximately 2 revolutions.

      3. Discharge Operation

        When the compression of the refrigerant gas is completed and the refrigerant pressure becomes high, the refrigerant gas discharges through the discharge port located in the center of the fixed scroll by pushing the discharge valve.

        A01HS8WE01
        Text in Illustration
        *1 Intake Port *2 Fixed Scroll
        *3 Rotating Scroll *4 Discharge Port
        *a Suction *b Compression
        *c Discharge - -

  4. DIAGNOSIS


    1. The air conditioning amplifier assembly has a diagnosis function. It stores a record of any air conditioning system failures in its memory in the form of Diagnostic Trouble Codes (DTCs). For details, refer to the Repair Manual.