MANUAL AIR CONDITIONER CONTROL SYSTEM [MANUAL AIR CONDITIONER]

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Outline

•  The climate control unit performs the following controls based on the signals from each switch/dial and the sensor.
―  Airflow temperature control
―  Airflow volume control
―  Airflow mode control
―  Air intake control
―  A/C compressor control

A/C cut-off control

•  Controls the A/C operation by switching the A/C relay on/off at the optimal timing according to engine operation conditions. (See A/C CUT-OFF CONTROL [SKYACTIV-G 2.0, SKYACTIV-G 2.5].)(See A/C CUT-OFF CONTROL [SKYACTIV-D 2.2].)


Block Diagram

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Outline of Control System

•  The manual air conditioner system functions based on the five basic types of controls and three supplementary functions.

Control name

Control part
•  Airflow temperature control
•  Airflow volume control
•  Airflow mode control
•  Air intake control
•  A/C compressor control
Climate control unit

Supplementary function
Fail-safe function
Sensor signal delay function
On-board diagnostic function


Control type transition by switch operation

Airflow temperature control, airflow volume control, airflow mode control

Operation switch

Airflow temperature control

Airflow volume control

Airflow mode control

Control prior to switch operation

Control prior to switch operation

Control prior to switch operation

Manual control

Manual control

Manual control

Defroster control
Airflow volume control dial
OFF
No change
OFF
No change
No change
1—7
No change
Manual control
No change
No change
MODE dial
VENT
No change
No change
Manual control
Manual control
BI-LEVEL
HEAT
DEF/HEAT
DEFROSTER
Temperature setting dial
No change
No change
No change
No change
A/C switch
No change
No change
No change
No change
RECIRCULATE switch
No change
No change
No change
No change
Rear window defogger switch
No change
No change
No change
No change

A/C compressor control, air intake control

Operation switch

A/C compressor control

Air intake control

Control prior to switch operation

Control prior to switch operation

Manual control

Manual control

Defroster control
Airflow volume control dial
OFF
OFF
No change
No change
1—7
No change
No change
No change
MODE dial
VENT
No change
No change
Manual control
BI-LEVEL
No change
No change
Manual control
HEAT
No change
No change
Manual control
DEF/HEAT
No change
No change
Manual control
DEFROSTER
Defroster control
Defroster control
Defroster control
Temperature setting dial
No change
No change
No change
A/C switch
Manual control
No change
Manual control
RECIRCULATE switch
No change
Manual control
Manual control
Rear window defogger switch
No change
No change
No change


Sensor Signal Delay Function

•  When the engine is restarted after being temporarily stopped, the ambient temperature sensor may detect a temperature higher than the actual ambient temperature.
•  To prevent this, if the engine coolant temperature exceeds 55 °C {131 °F}, control of each system is performed based on the ambient temperature data before the engine was stopped, which is stored in the climate control unit.

Airflow Temperature Control

•  The climate control unit drives the air mix actuator according to the operation of the temperature setting dial.
•  The air mix actuator changed air mix door position.

Airflow Volume Control

•  The climate control unit changes the blower motor applied voltage (airflow volume) in seven steps according to the operation of the airflow volume control dial.

Airflow volume control dial

Blower motor applied voltage (reference: when the airflow mode is set to the BILEVEL)

Except during i-stop control (engine stop )

During i-stop control (engine stop )
1st
3.8 V
4.2 V
2nd
5.2 V
5.2 V
3rd
6.9 V
6.3 V
4th
8.6 V
7.4 V
5th
10.0 V
8.3 V
6th
11.4 V
9.4 V
7th
14.0 V
14.0 V


Retard control

•  The retard control retards the ignition voltage to the blower motor for approx. 1 s and operates the motor to prevent blower motor damage due to inrush current when the blower motor switch is switched.


Airflow Mode Control

•  The climate control unit switches the airflow mode based on the MODE dial operation.

Airflow mode

Operation switch

Air vent
VENT
Mode dial
CENTER VENT, SIDE VENT
BI-LEVEL
CENTER VENT, SIDE VENT, FRONT HEAT, REAR HEAT
HEAT
FRONT HEAT, REAR HEAT, SIDE DEMISTER (low volume), DEFROSTER (low volume), SIDE VENT (low volume)
DEF/HEAT
FRONT HEAT, REAR HEAT, SIDE DEMISTER, DEFROSTER, SIDE VENT (low volume)
DEFROSTER
SIDE DEMISTER, DEFROSTER, SIDE VENT (low volume)


Air Intake Control

•  The climate control unit switches the air intake mode based on the RECIRCULATE switch operation.

Air intake mode (RECIRCULATE switch operation)

RECIRCULATE indicator light
FRESH → RECIRCULATE
On
RECIRCULATE → FRESH
Off


Defroster control

•  The defroster control improves the defrosting effect.
•  When the defroster switch turns on, the climate control unit fixes the air intake mode to FRESH.
•  The air intake is fixed at FRESH even if it has been set to RECIRCULATE manually.


RECIRCULATE mode control under severe heat

•  When the vehicle is driven at a very low speed with the A/C on under severe heat conditions, the climate control unit may change the air intake mode from FRESH to RECIRCULATE automatically. Due to this, load on the A/C compressor is reduced.


A/C Compressor Control

•  The climate control unit sends the A/C signal to the PCM based on the signals sent from the A/C switch, airflow volume control dial, and evaporator temperature sensor.
•  The PCM turns the A/C relay on/off based on the input signals from the A/C signal and A/C pressure sensor and controls the A/C compressor (magnetic clutch) operation.
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A/C signal on/off control

•  When the A/C switch and fan switch are turned on, the climate control unit turns the A/C signal (magnetic clutch) on/off based on the temperature of the air passing through the evaporator.
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•  When the fan switch and A/C switch are turned on, the climate control unit controls the surface temperature of the evaporator so that it is within a certain range to prevent the evaporator from freezing.
•  When the ambient temperature is low, the climate control unit sets the A/C signal (magnetic clutch) off-temperature to low to prevent window fogging.