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A/C condenser & receiver drier
It is installed in front of vehicle and condenses vapor
refrigerant into low temperature and high pressure liquid
refrigerant. The receiver drier is built in it.Ambient temperature sensor
It is mounted to the front section of the
vehicle and detects the ambient
temperature to send the voltage value
according to the resistance change to
the heater and A/C control assembly.
Engine ECU
It controls the A/C compressor, electric fan
and PTC heater according to the signal from
the A/C control panel.
Expansion valve
It is mounted to the inlet of the evaporator
core and supplies the appropriate quantity
of refrigerant to the evaporator.
Integrated receiver drier
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Intake sensor
It is mounted to the side of
evaporator core and detects the
temperature of the evaporator
core.Water temperature
sensor
It is mounted to the heater pipe
part and detects the coolant
temperature.
3) Air Conditioner Module Layout
Temp actuator
It changes the air mix door
opening according to the
control command from the
heater and A/C control
assembly.Evaporator core
It cools the surrounding air by
passing through the low-
temperature and low-pressure
refrigerant sprayed from the
expansion valve.
Heater core
It is mounted to the left-hand of
the air conditioner module and
heats the indoor using the heat
of the engine coolant.
Mode actuator
It controls the air outlet damper
to the five directions according
to the control command from
the heater and A/C control
assembly.
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(2) Temperature control
The blowing air temperature is controlled by the temp actuator and the set temperature can be checked
via the LCD display.
Manual control
The discharge air temperature is controlled by the temperature control dial. The driver can select one
of the 31 levels.
Auto control
When pressing the AUTO switch, "AUTO" is shown on the display and the fan speed and air distribution
mode are adjusted automatically to keep interior temperature to the set temperature. In full AUTO mode,
the FATC receives various signals such as the indoor temperature, ambient temperature, engine coolant
temperature, sunlight, from different sensors to control the A/C compressor, mode actuator, intake
actuator, temp actuator, blower motors, etc. to keep indoor environments fresh.
Max. cooling/heating control (AUTO mode)
If the temperature is set to the lowest level (Lo) or highest level (Hi), the system will go into the maximum
cooling or maximum heating mode regardless of the sensor signals.
Set
temp.A/C
compressorAir outlet
(mode)Air inletBlower
voltageTemp actuator
LO ON Vent Recirculation 10.5 V Max. cooling position
HI OFF Footwell Fresh air 10.5 V Max. heating position
Temperature control dial
LCD display (temperature view)
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Initial fan speed control for cooling/heating
Cooling start control
by the air flow from the vent. Therefore, at the initial operation stage, the hot air is discharged to the
windshield (DEF mode) for about 5 seconds. -
Heating start control
When the engine coolant temperature is low or the wind temperature is not warmed up sufficiently,
the driver might feel uncomfortable by the air flow from the vent. Therefore, the fan speed is set to the
1st stage and the cool air is sent to the windshield until the coolant temperature increases to the
proper level (DEF mode). As the engine coolant temperature goes up, the mode is changed to
Defrost & Foot mode or AUTO mode to increase the speed of blower motor. This control is cancelled
control time must not exceed 10 minutes. -
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(6) A/C control
The air conditioner is controlled by the A/C compressor of the engine ECU according to the signal from
the heater and A/C control assembly. The driver can see the air conditioner operation through the LCD
display and the indicator of the A/C switch.
Manual control
Pressing the A/C switch or selecting defrost mode turns on the A/C.
Auto control
The A/C is controlled in accordance with the indoor temperature and ambient temperature.
or below) in winter, the compressor is turned off to protect the A/C compressor.
A/C switch
LCD display (A/C operation view)
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(6) A/C control
The air conditioner is operated at the defroster mode and MAX air conditioner mode and when the A/C
switch is turned to "ON" position. It is controlled by the A/C compressor of the engine ECU according to
the signal from the heater and A/C control assembly. The driver can see that the A/C has been activated
when an indicator lamps at the A/C switch and MAX A/C switch comes on. If the intake sensor detects
the freezing of the evaporator core, it stops the air conditioner by turning off the compressor.
MAX A/C control
This is designed for increasing driver comfort. When the switch is pressed, the air conditioner is
operated and vent and recirculation modes are selected automatically. The discharge temperature and
fan speed are regulated depending on the driver's choice.
A/C switch
MAX A/C control switch
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5. PTC HEATER OPERATION PROCESS
1) PTC Heater Input/Output Factors
The engine ECU controls the PTC (Positive Temperature Coefficient) heater system by adjusting the
power supplied to the PTC system according to the two measured temperature values from the engine
coolant temperature sensor and HFM sensor. This system is mounted to the heater air outlet in the air
condition system module and heats the air which flows to the passenger room. Since the PTC system is
heated by the electrical power, the electric load and alternator capacity is greater than the conventional
one. The PTC is not operated when a) the engine is cranking, b) the battery voltage is below 11 V, c) the
glow plug is being preheated.
The ceramic PTC features that the resistance rises quickly in a certain temperature range. The PTC
heater has 3 circuits with power of 330 W. While only 1 circuit in the PTC heater is connected during
PTC1 operation, 2 circuits are connected during PTC2 or PTC3 operation.
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2) Control Condition For PTC Heater
Operation Operating condition PTC heater status
HI mode operation
(PTC2, 3)PTC heater operates in
"HIGH" mode if operating
conditions are met
LO mode operation
(PTC1)PTC heater operates in
"LOW" mode if operating
conditions are met
Conditions for
deactivating
Air conditioner blower switch OFF
When the ambient temperature sensor is
faulty (short or open circuit in the wiring)
Engine is cranking
Battery voltage is 11 V or less
Glow plug is being preheated (Glow indicator
comes on) -
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Conditions for PTC heater "LOW" operation mode (2nd step)