AIR CONDITIONING SYSTEM SYSTEM DESCRIPTION


  1. GENERAL


    1. The air conditioning system has the following controls.

      Control Outline
      Neural Network Control This control is capable of performing 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 similar to that of a human brain.
      Automatic Recirculation Control*1 Automatically changes the air inlet mode to fresh air or recirculation air mode according to the level of harmful elements in the outside air, cabin temperature, and outside temperature.
      Outlet Air Temperature Control Based on the temperature set by the temperature control dial, the neural network control calculates outlet air temperature based on input signals from various sensors.
      Left and Right Independent Control The temperature settings for the driver and front passenger are controlled independently in order to provide separate vehicle interior temperatures for the right and left sides of the vehicle. Thus, air conditioning that accommodates the occupants preferences has been realized.
      Blower Control Controls the blower motor in accordance with the airflow volume that has been calculated by the 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 the neural network control.
      In accordance with the engine coolant temperature, ambient air temperature, amount of sunlight, required blower, outlet temperature and vehicle speed conditions, this control automatically switches the blower outlet to foot and defroster mode to prevent the windows from becoming fogged up when the ambient air temperature is low.
      Air Inlet Control Automatically controls the air inlet control damper to help achieve the calculated outlet air temperature that is required.
      Drives the air inlet control servo motor according to the operation of the air inlet control switch and moves the dampers to the fresh or recirculation position.
      Compressor Control Through the calculation of the target evaporator temperature based on various sensor signals, the air conditioning amplifier optimally controls discharge capacity by regulating the opening extent of the compressor solenoid valve.
      The air conditioning amplifier compares the pulley speed signals (transmitted by the lock sensor located on the compressor) with the engine speed signal (which are transmitted by the ECM (crankshaft position sensor)). When the air conditioning amplifier determines that the pulley is locked, it turns off the magnetic clutch.
      Defroster Control Defroster control logic is used to improve defroster performance.
      Rear Defogger Control

      When the engine switch is on (IG) and the rear defogger switch is pushed, the system is activated to keep the defogger heater on for approx. 15 minutes. However, the operating time of the rear defogger can be extended up to approx. 60 minutes when both of the following requirements are met:


      • Ambient Temperature: 0°C (32°F) or less

      • Vehicle Speed: 37.3 mph (60 km/h) or more
      Memory Call Control

      Memorizes the last air conditioning settings when the engine switch is turned from on (IG) to off in accordance with the ID code of the key that is used to operate the vehicle. The key-linked memory call control then recalls the settings if the key is used when the engine switch is turned on (IG). This function operates when both of the following conditions are met:


      • Inside of the outside door handle is touched or the driver door is unlocked using the unlock button, and then the driver door is opened.

      • Engine switch is turned on (IG).
      Diagnosis A Diagnostic Trouble Code (DTC) is stored in the memory when the air conditioning amplifier detects a problem with the air conditioning system.

      • *1: w/ Smog Ventilation Sensor

  2. NEURAL NETWORK CONTROL


    • In the previous automatic air conditioning systems, the A/C amplifier 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 effecting 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 A/C amplifier. The A/C amplifier can then effect control to provide enhanced air conditioning comfort.

    • 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 A/C amplifier controls the servo motors and blower motor in accordance with the control volumes that have been calculated by the neural network control.

    A019M3OE15

  3. AUTOMATIC RECIRCULATION CONTROL (w/ Smog Ventilation Sensor)


    1. When the automatic recirculation control is operating, the A/C amplifier automatically changes the air inlet mode to fresh air or recirculate air mode based on signals from the smog ventilation sensor, ambient temperature and room temperature sensors when AUTO air inlet mode is selected.

      A019NTYE04

      1. The A/C amplifier detects harmful elements (CO, HC, and NOx) based on a smog ventilation sensor signal and automatically switches the air inlet mode to recirculate air mode to prevent such harmful elements from entering the cabin.

      2. The A/C amplifier detects cabin temperature based on a room temperature sensor signal and automatically switches the air inlet mode to recirculate air mode to prevent the cabin temperature from becoming too high.

      3. The A/C amplifier detects the outside temperature based on an ambient temperature sensor signal and automatically switches the air inlet mode to fresh air mode to prevent the windshield from fogging up.

        Note

        The smog ventilation sensor cannot detect elements such as the smoke from a bonfire or factory exhaust, foul or animal odors, and dirt or dust particles. Therefore, the air inlet mode is not switched automatically in accordance with those elements.

  4. MODE POSITION AND DAMPER OPERATION


    1. Mode Position and Damper Operation

      A019NRXE01
      Functions of Main Dampers
      Control Damper Operation Position Damper 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 Varies the mixture ratio of warm air and cool air in order to regulate the temperature continuously between hot and cold.
      Air Outlet Control Damper

      DEF

      A019PDO       		E, K, N, R, U Defrosts the windshield through the center defroster, side defrosters and side registers.

      FOOT/DEF

      A019PAM       		F, K, N, Q, S Defrosts the windshield through the center defroster, side defrosters and side registers while air is also blown out from the front and rear footwell register ducts.

      FOOT

      A019LLH       		G, K, N, Q, S Air blows out of the front and rear footwell register ducts, and side registers. In addition, air blows out slightly from the center defroster and side defrosters.

      BI-LEVEL

      A019P16       		H, J, M, P, T Air blows out of the front center register, rear center register, side registers and front and rear footwell register ducts.

      FACE

      A019OCV       		H, I, L, O, U Air blows out of the front center register, rear center register and side registers.

  5. AIR OUTLETS AND AIRFLOW VOLUME


    1. Air Outlets and Airflow Volume

      A019MUWE01
      Indication Mode FACE FOOT DEF
      CTR SIDE RR FR RR F
      A B C D E
      A019OCV FACE A019P30 A019P30 A019P30 A019NWV A019NWV A019NWV
      A019P16 B/L A019JOX A019JOX A019JOX A019JOX A019JOX A019NWV
      A019LLH FOOT A019NWV A019JOX A019JOX A019P30 A019P30 A019P0U
      A019PAM F/D A019NWV A019JOX A019JOX A019JOX A019JOX A019P30
      A019PDO DEF A019NWV A019JOX A019NWV A019NWV A019NWV A019P30

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

  6. A/C COMPRESSOR


    1. General:


      1. The A/C compressor is a continuously variable capacity type in which its capacity can be varied in accordance with the cooling load of the air conditioning system.

      2. The A/C compressor consists of a pulley, shaft, lug plate, swash plate, piston, shoe, crank chamber, cylinder, A/C lock sensor, solenoid control valve with built-in Crank chamber to Suction passage (CS) valve, A/C mass flow sensor, oil separator and variable suction side throttle.

      3. The A/C pulley with built-in magnetic clutch has an A/C lock sensor that detects whether the A/C compressor is locked.

      4. A solenoid valve is provided to enable the suction pressure to be controlled as desired.

      5. The Crank chamber to Suction passage (CS) valve, built into the solenoid control valve, operates in accordance with the suction pressure.

      6. The oil separator is installed in the refrigerant passage to separate A/C compressor oil from the refrigerant that is discharged. This helps to prevent the A/C compressor oil from flowing into the air conditioning system and reducing cooling effectiveness.

    2. Solenoid Valve Operation:


      1. The crank chamber is connected to the suction passage. A solenoid valve is provided between the suction passage (low pressure) and the discharge passage (high pressure).

      2. The solenoid valve operates under duty cycle control in accordance with the signals from A/C amplifier.

      3. When the solenoid valve closes (solenoid coil is energized), a difference in pressure is created and the pressure in the crank chamber decreases. Then, the pressure that is applied to the right side of the piston becomes greater than the pressure that is applied to the left side of the piston. This compresses the spring and tilts the swash plate. As a result, the piston stroke increases and the discharge capacity also increases.

      4. When the solenoid valve opens (solenoid coil is not energized), the difference in pressure disappears. Then, the pressure that is applied to the left side of the piston becomes the same as the pressure that is applied to the right side of the piston. Thus, the spring elongates and eliminates the tilt of the swash plate. As a result, there is no piston stroke, and the discharge capacity is reduced.

    3. CS Valve Operation:


      1. The CS valve consists of passage A and passage B. If the vehicle is left parked for a long period, refrigerant may accumulate in the crank chamber due to the heat capacity difference.

      2. The solenoid control valve is controlled by the A/ C amplifier. While the A/C compressor is operating, the solenoid control valve pushes down the CS valve rod and open passage A.

      3. Under the above condition, only if the refrigerant accumulates in the crank chamber, the crank chamber pressure will become high. As a result, the bellows will contract because of the pressure difference with its internal pressure (vacuum), and opens passage B.

      4. This causes the accumulated refrigerant to be drawn in via passage A and B, clearing the accumulated refrigerant earlier and ensuring a more immediate cooling effect.

  7. A/C MASS FLOW SENSOR

    The A/C mass flow sensor, which is mounted on the A/C compressor, is used to detect the amount of refrigerant flow. The A/C mass flow sensor converts the amount of refrigerant flow that is detected to a voltage value to send it to the A/C amplifier. The voltage value sent from the A/C mass flow sensor changes depending on the amount of refrigerant flow. As the amount of refrigerant flow becomes larger, the voltage becomes lower. As the amount of refrigerant flow becomes smaller, the voltage becomes higher. The A/C amplifier supplies 5 V to the A/C mass flow sensor and monitors change in the voltage value sent from the A/C mass flow sensor. The A/C amplifier then sends a signal to the ECM via CAN communication to allow the ECM to control the engine speed while the air conditioning is on.

  8. A/C LOCK SENSOR (for 2GR-FE)

    The A/C lock sensor sends A/C pulley speed signals to the A/C amplifier. The A/C amplifier determines whether the A/C compressor is locked or not by using those signals and engine speed signals.

  9. EVAPORATOR TEMPERATURE SENSOR

    The evaporator temperature sensor detects the temperature of the cool air immediately through the evaporator in the form of resistance changes, and outputs it to the A/C amplifier.

  10. BLOWER MOTOR

    The blower motor has a built-in blower controller, and is controlled using duty control performed by the A/C amplifier.

  11. BUS CONNECTOR (AIR CONDITIONING HARNESS)


    1. A BUS connector is used for the wire harness connection that connects each servo motor to the A/C amplifier.

      A019KB9E04

    2. Each BUS connector has a built-in communication/driver IC which communicates with each servo motor connector, actuates the servo motor, and has a position detection function. This enables bus communication for the servo motor wire harness, for a more lightweight construction and a reduced number of wires.

      A019O95E13

  12. SERVO MOTOR

    The pulse pattern type servo motor consists of a printed circuit board and a servo motor. The printed circuit board has three contact points, and can transmit two ON-OFF signals to the A/C amplifier based on the difference of the pulse phases. The BUS connector can detect the damper position and movement direction with these signals.

    A019KNTE04

  13. ROOM TEMPERATURE SENSOR

    The room temperature sensor detects the cabin temperature based on changes in the resistance of its built-in thermistor and sends a signal to the A/C amplifier.

  14. AMBIENT TEMPERATURE SENSOR

    The ambient temperature sensor detects the outside temperature based on changes in the resistance of its built-in thermistor and sends a signal to the A/C amplifier.

  15. SOLAR SENSOR


    1. The solar sensor consists of a photo diode, two amplifier circuits for the solar sensor, and frequency converter circuit for the light control sensor.

    2. The solar 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 the LH and RH sides (2 directions) and outputs these sunlight strength signals to the A/C amplifier.

      A019NKKE11

  16. A/C PRESSURE SENSOR

    The A/C pressure sensor detects the refrigerant pressure and outputs it to the A/C amplifier in the form of voltage changes.

  17. MEMORY CALL CONTROL


    1. Memory call control memorizes the air conditioning system settings together with the ID code of the key that is being used.

    2. When a key with memory is used to unlock the door, the driver door is opened and the engine switch is turned on (IG), the memorized air conditioning system settings will be recalled.

    3. The certification ECU (smart key ECU) will recognize the key during the unlock operation by reading the registered ID code.

    4. Using this control, the air conditioning system setting preference that corresponds to each key can be memorized, enhancing usability.

    5. The following air conditioning system settings can be memorized:

      Setting Condition
      A/C Switch On or Off
      AUTO Switch On or Off
      Temperature Setting Driver Side LO, 16 to 30°C (61 to 86°F) or HI
      Front Passenger Side LO, 16 to 30°C (61 to 86°F) or HI
      Blower Fan Speed Level 1 to 7
      Air Inlet Mode Fresh or Recirculate
      Air Outlet Mode Face, Bi-Level, Foot, Foot/Defroster or Defroster
      DUAL Switch On or Off

      Tech Tips

      Memory call control can be cancelled or re-enabled using the intelligent tester. When a new key is added, key ID code registration is necessary.