System Description

The air conditioning system has the following controls:

1. Mode Position and Damper Operation
   Fig 1: Mode Position And Damper Operation Diagram

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   Fig 2: Functions Of Main Dampers

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1. Air Outlets and Airflow Volume
   Fig 3: Identifying Air Outlets And Airflow Volume

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   The size of the circle O indicates the proportion of airflow volume.

1. General
   1. The A/C compressor is a continuously variable capacity type in which its capacity varies in accordance with the cooling load of the air conditioner.
   2. This compressor consists of the shaft, lug plate, piston, shoe, crank chamber, cylinder, and solenoid control valve.
   3. The solenoid control valve adjusts the suction pressure so that the suction pressure can be controlled as desired.
   4. A plastic DL (Damper Limiter) type A/C pulley is used.
      Fig 4: Identifying A/C Compressor Components

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2. Operation
   1. The crank chamber is connected to the suction passage. A solenoid control valve is provided between the suction passage (low pressure) and the discharge passage (high pressure).
   2. The solenoid control valve operates under duty cycle control in accordance with the signals from the air conditioning amplifier.
      Fig 5: A/C Compressor Operation Diagram

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   3. When the solenoid control 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 lug plate. As a result, the piston stroke increases and the discharge capacity increases.
      Fig 6: A/C Compressor Operation Diagram (When Solenoid Control Valve Close)

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   4. When the solenoid control 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 lag plate. As a result, there is small piston stroke and the discharge capacity decreases.
      Fig 7: A/C Compressor Operation Diagram (When Solenoid Control Valve Open)

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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 Air Conditioning amplifier.

The evaporator temperature sensor detects the temperature of the cool air immediately past the evaporator in the form of resistance changes, and outputs it to the Air Conditioning amplifier.

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

1. General
   1. The PTC heater is located above the heater core in the air conditioner unit.
   2. The PTC heater consists of a PTC element, aluminum fin, and brass plate. When current is applied to the PTC element, it generates heat to warm the air that passes through the unit.
2. PTC Heater Operating Conditions
   1. The ON/OFF function of the PTC heater is controlled by the air conditioning amplifier in accordance with the water temperature, ambient temperature, engine speed, air mix setting, and electrical load (generator power ratio). For example, the number of the operating PTC heaters varies by the water temperature as in the graph below.
      Fig 8: Heating Value Pattern Graph

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