AIRFLOW TEMPERATURE CONTROL OPERATION
id074000102300
Airflow Temperature Automatic Control
• Based on the set temperature and sunlight intensity, the climate control unit calculates the air mix actuator opening angle characteristic. The higher the sunlight intensity, the lower the air mix actuator opening angle characteristic.
• The climate control unit compares the air mix actuator opening angle characteristic, the present ambient temperature and target temperature (control computation value T1) and determines a basic angle of opening for the air mix actuator.
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1
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Air mix actuator basic opening
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2
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MAX HOT
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3
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MAX COLD
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4
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Ambient temperature
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5
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Low
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6
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High
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7
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When the sunlight intensity is low
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8
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When the sunlight intensity is high
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9
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Air mix actuator opening angle characteristic (A/C off mode)
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10
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Air mix actuator opening angle characteristic (A/C on mode)
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Correction
Air intake correction
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• When the A/C mode is off, the air mix actuator opening angle is corrected to prevent airflow temperature rise when the air intake mode is switched from fresh air to recirculated air. In addition, this correction retards the air mix actuator operation to prevent a sudden drop in airflow temperature.
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1
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Air mix actuator opening angle delay
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2
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Air intake mode
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3
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Air mix actuator opening angle correction amount
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4
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HOT
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5
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COLD
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6
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FRESH
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7
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RECIRCULATE
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8
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Time
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A/C correction
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• When the A/C compressor is switched from A/C ON mode to OFF mode, the basic opening angle of the air mix actuator is switched from the A/C ON mode opening angle to the A/C OFF mode opening angle. This prevents a rise in airflow temperature. In addition, this correction retards the air mix actuator operation to prevent a sudden drop in airflow temperature.
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1
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Air mix actuator opening angle delay
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2
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A/C mode
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3
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Air mix actuator opening angle correction amount
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4
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HOT
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5
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COLD
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6
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Time
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MAX HOT and MAX COLD correction
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• When the temperature is set to MAX HOT (temperature setting dial is turned to the right), air mix actuator is completely open (100%), when set to MAX COLD (temperature setting dial is turned to the left), it is firmly closed.
Coolant temperature correction
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• There are cases where the engine coolant temperature is lowered when continuously idling in extremely low outside temperature. To prevent lower airflow temperature in this situation, the climate control unit adjusts the HOT air mix actuator to opening according to the engine coolant temperature. However, coolant temperature correction does not operate when the ambient temperature is above 10 °C {50 °F}.
Fail-safe function
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• When the potentiometer of air mix actuator is malfunctioning, the air mix door is fixed. Under this situation, if the ignition switch is turned to the ON/LOCK position, the air mix door is controlled to be fully opened (MAX HOT) or closed (MAX COLD) based on the ambient temperature. In addition, the door is fully closed (MAX COLD) at the set temperature MAX COLD (15.0: European (L.H.D. U.K.) specs. 18.0: Australian, General (L.H.D. R.H.D.) specs.), and fully opened (MAX HOT) at the set temperature MAX HOT (29.0: European (L.H.D. U.K.) specs. 32.0: Australian, General (L.H.D. R.H.D.) specs.).
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1
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Ambient temperature
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2
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MAX COLD
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3
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MAX HOT
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-
• If the air mix door locks and the target air mix actuator opening angle is not reached within 20 s, the air mix actuator drive signal is stopped to prevent burning the motor.