AIRFLOW VOLUME CONTROL OPERATION [FULL-AUTO AIR CONDITIONER]
id0740a1102600
Airflow volume automatic control
• The climate control unit calculates the blower motor applied voltage characteristic based on the set temperature and ambient temperature.
• Compares the differences among this blower motor applied voltage characteristic and the target temperature (Calculated control value T2) and then determines the blower motor applied voltage (AUTO voltage).
• Calculated control value T2 is the target cabin temperature as set by the climate control unit based on differences between the set temperatures and temperatures input from the sensors. Calculated control value T2 is constantly calculated according to the set temperature and the changes in the signals input from the sensors.
Correction
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Engine coolant temperature correction (warm-up correction)
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• Controls the blower motor applied voltage according to the increase in engine coolant temperature to prevent discomfort caused by a high volume of cold air blown from the vents after the engine is started in winter. However, the engine coolant temperature correction is not performed during defroster correction and when the cabin temperature is
20 °C {68 °F} or more, and the airflow mode is in VENT mode.
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Mild start correction
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• Limits blower motor applied voltage for
3 s after the blower motor is started in summer to prevent discomfort caused by a high volume of hot air blown from the vent. However, the mild start correction is not performed when the cabin temperature is
20 °C {68 °F} or less and when the airflow is in any mode other than VENT.
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MAX HOT and MAX COLD correction
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• When the temperature is set to 29 (right end of temperature setting dial), the blower motor applied voltage is fixed at AUTO-HI, and when set to 15 (left end of temperature setting dial), it is fixed at MAX-HI. However, MAX HOT correction is not performed during engine coolant correction.
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Correction
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Set temperature
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Blower motor applied voltage
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MAX HOT correction
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29
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12.1 (V):AUTO-HI
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MAX COLD correction
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15
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14.6 (V): MAX-HI
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Window fogging prevention correction at engine start-up
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• The A/C compressor does not turn on due to PCM A/C cut-off control just after the engine is started. Therefore, the windshield and front door glass are easily fogged when the heater is turned on and air blows from the defroster. To prevent this, blower motor applied voltage is fixed at 0 V for 6 s after the ignition switch is turned to the ON position. However, window fogging prevention correction at start-up is not performed when the airflow mode is in any mode other than HEAT, HEAT/DEF or defroster.
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Starting compensation correction
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• When the blower motor is started at the lowest speed (3.2 V), the blower motor applied voltage is fixed at 4.4 V for 2 s to stabilize blower motor start-up operation.
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Defroster correction
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• To improve defrosting of the windows, a (+2 V) correction is added to the blower motor applied voltage when the defroster switch is turned on.
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Excess current prevention function during start-up
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• When the blower motor is started-up from the stopped status with a blower motor applied voltage of 4.4 V or more, the blower motor applied voltage is fixed at 4.4 V for 1 s to prevent damage to the MOS FET from excessive current.
Airflow volume manual control
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• The blower motor applied voltage (airflow volume) can be switched in seven steps using the fan switch.
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Fan switch
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Blower motor applied voltage
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1st
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4.4 V
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2nd
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6.1 V
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3rd
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7.8 V
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4th
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9.5 V
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5th
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10.8 V
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6th
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12.1 V
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7th
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14.6 V
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