Page 698 of 1575
2007 > 2.7L V6 GASOLINE >
INSPECTION
1.Ignition "OFF"
2. Disconnect ambient temperature sensor.
3. Check the resistance of ambient temperature sensor between terminals 1 and 2 whether it is changed by changing
of the ambient temperature.
Specification
Ambient temperature [°C(°F)] Resistance between terminals 1and 2 (kΩ)
- 10(14) 164 ± 3%
0 (32) 97.5 ± 3%
10 (50) 59.6 ± 3%
20 (68) 37.5 ± 3%
4.If the measured resistance is not specification, substitute with a known- good ambient temperature sensor and
check for proper operation.
5. If the problem is corrected, replace the ambient temperature sensor.
REPLACEMENT
1.Disconnect the negative ( - ) battery terminal.
2. Remove the front bumper. (Refer to BD group)
3. Remove the ambient temperature sensor (A).
4.Installation is the reverse order of removal.
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Page 703 of 1575
Page 705 of 1575
2007 > 2.7L V6 GASOLINE >
DESCRIPTION
1.Humidity sensor is located at the lower crush pad and detected in - car humidity for in - car humidity control.
2. If ambient air temperature or in - car humidity is outside certain range, it will turn on A/C to control in - car humidity
preventing in car fogging.
Air conditioner operation depends on ambient temperature and humidity.
Page 706 of 1575
2007 > 2.7L V6 GASOLINE >
INSPECTION
1.Ignition "ON"
2. Using the scan tool.
3. Check the frequency of humidity sensor between terminals 2 and 3.
Humidity (%) Frequency between terminals 2and 3 (Hz)
30 6976 ± 5%
50 6728 ± 5%
60 6600 ± 5%
70 6468 ± 5%
80 6330 ± 5%
90 6186 ± 5%
4. If the measured resistance is not specification, substitute with a known- good humidity sensor and check for proper
operation.
5. If the problem is corrected, replace the Humidity sensor.
REPLACEMENT
1.Disconnect the negative ( - ) battery terminal.
2. Remove the center facia lower panel (A). (Refer to BD group)
3. Disconnect the humidity sensor connector (A).
4. Loosen 2 screws and then remove the humidity sensor (B).
5.Installation is the reverse order of removal.
Page 713 of 1575

2007 > 2.7L V6 GASOLINE >
REPLACEMENT
1.Disconnect the negative ( - ) battery terminal.
2. Recover the refrigerant with a recovery/ recycling/ charging station. (Refer to HA - 8)
3. When the engine is cool, drain the engine coolant from the radiator.
4. Remove the bolts (A) and the expansion valve (B) from the evaporator core.
Plug or cap the lines immediately after disconnecting them to avoid moisture and dust contamination.
5.Disconnect the inlet (A) and outlet (B) heater hoses from the heater unit.
Engine coolant will run out when the hoses are disconnected; drain it into a clean drip pan. Be sure not to let
coolant spill on electrical parts or painted surfaces. If any coolant spills, rinse it off immediately.
6. Remove the crash pad (Refer to BD group).
7. Remove the cowl cross bar assembly. (Refer to BD group)
8. Disconnect the connectors from the temperature control actuator, the mode control actuator and the evaporator
temperature sensor.
9. Remove the heater & blower unit after loosening 3 mounting bolts.
Page 729 of 1575

3.The two coolant temperature sensors are installed to the heater inner. The sensor valves determine heater
operation.
4. One of the temperature sensors functions to prevent the heater from overheating.
If the sensor temperature valve exceeds 125°C, the fuel will be cut and the heater will be deactivated by the
determination of the overheating of the heater.
The other temperature sensor determines the operation mode of the fuel fired heater.The temperature of this
sensor enables to activate the heater at full load(5kw) or half load(2.5kw).
• The coolant temperature shown on the above Figure is the value of the inner sensor and the actual coolant
temperature is higher about 5°C ~7°C than the above value.
OPERATION
Switch on/ Operation start
The fuel fired heater is operated when the coolant temperature is below 68°C and the ambient temperature is below
2°C after starting the engine.
At this time, the glow plug and combustion air fan are operated first and after 30 seconds, the dosing pump is
operated with stopping the combustion fan for 3 seconds.
After that, the operation of the fan increases continuously until it approaches to full load within 56 seconds. If fuel
supply reaches to full load the glow plug does not operate and the operation of the fan reaches to full load.
After that the glow plug monitors ignition condition as a flame sensor for 45 seconds.
The above operation procedure is done automatically and in case the ignition fails, the above operation will be done
again automatically.
If the condition of ignition failure sustains continuously, fuel supply and fan operation will be stopped and error codes
will be stored to find cause of failure.
Generally, the cause of ignition failure during combustion is caused by the automatic re- operation of the above
procedure.
Operation for heating
The fuel fired heater operates at full load when the coolant temperature is below 68°C and the ambient temperature is
below 2°C after starting the engine.
It operates at half load when the coolant temperature is 74°C and it operates at idle mode when the coolant
temperature is 78°C.
The fuel fired heater during the transformation process does a cleaning function from the half mode to the idle mode.
At idle mode, all components do not work.
The fuel fired heater operating at idle mode turns into the half load when the coolant temperature is 74°C. At this time,
if the coolant temperature drops again below 68°C, the heater operates with full load and turns into the idle mode if
the temperature is 78°C.
This serial operating process is performed automatically.
Key switch off / Operation stop
The fuel fired heater ECU stops the operation of the fuel pump and cuts fuel supply when shutting off the engine
during the heater operation.
The heater conducts cleaning operation at this time.
This is a process of burning the fuel completely supplied in the heater inner.
In this process, the glow plug and combustion air fan are operated.
Page 731 of 1575

2007 > 2.7L V6 GASOLINE >
INSPECTION
OPERATION TEST
Fuel-fired heater operation test by force using Hi-Scan
1. Start the engine.
2. Connect the Hi - Scan to the vehicle.
3. Select "SORENTO" and then select "FUEL FIRED HEATER".
4. Select "04. ACTUATION TEST" mode.
5. Select "PREFILLING + HEATING" to conduct the performance test after replacing the fuel fired heater system.
Fuel supply and heating will be initiated if the "F1 key STRT" is pressed.
However, a repair or replacement of the components related to the fuel line system in the fuel- fired heater were not
done, operate the component by force after selecting the appropriate item from the menu screen.
Do not operate the system by force with selecting the “ PREFILLING + HEATING ” option if no repair for the
fuel line relating components has been done.
This means the fuel is in the fuel line.If an excessive fuel is supplied, it may cause smoke and abnormal
"Banging" noise when the fuel is burned.
If the "F2 KEY STOP" is pressed, operation test is stopped.
For self - diagnosis test and sensors outputs during compulsory operation test, press "ESC KEY".
When a self - diagnosis test is completed, disconnect the self - diagnosis connector or press "F2 KEY STOP"
from the "PREFILLING + HEATING" menu to stop the compulsory operation.
In case of selecting the individual part (ex. Combustion air fan, water pump, ), press "ESC KEY" to stop the
test.
In case of selecting the "PREFILLING + HEATING" option, about 2 minutes are required to conduct cleaning
process after pressing the "F2 KEY STOP".
It is a normal process to burn the fuel left in the fuel line.
6. To conduct self diagnosis test, press "ESC" and then "01. DIAGNOSTIC TROUBLE CODES" option.
7.Select "02. CURRENT DATA" to view the current status of the components.