2008 TOYOTA SIENNA cooling

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The gauge indicates the engine coolant
temperature when the engine switch is
on. The engine operating temperature
will vary with changes in weather and
engine load.
If the needle moves into the red zone,
your engine is too hot. If your vehicle
overheats, stop your vehicle and allow the
engine to cool.
Your vehicle may overheat during severe
operating conditions, such as:
Driving up a long hill on a hot day.
Reducing speed or stopping after high
speed driving.
Idling for a long period with the air
conditioning on in stop−and− go traffic.
Towing a trailer.
NOTICE
Do not remove the thermostat in
the engine cooling system as this
may cause the engine to overheat.
The thermostat is designed to con-
trol the flow of coolant to keep the
temperature of the engine within
the specified operating range.
 Do not continue driving with an
overheated engine. See “If your ve-
hicle overheats” on page 470 in
Section 4.
The tachometer indicates engine speed
in thousands of rpm (revolutions per
minute). Use it while driving to select
correct shift points and to prevent en-
gine lugging and overrevving.
Driving with the engine running too fast
causes excessive engine wear and poor
fuel economy. Remember, in most cases
the slower the engine speed, the greater
the fuel economy.
NOTICE
Do not let the indicator needle get
into the red zone. This may cause
severe engine damage.
Tachometer

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If following another vehicle on a dusty
road, or driving in windy and dusty
conditions, it is recommended that the
air intake selector be temporarily set to
RECIRCULATE, which will close off the
outside passage and prevent outside
air and dust from entering the vehicle
interior.Heating
For best results, set controls to:
Fan speed— Any setting except “OFF”
Temperature— To w a r d s WARM
(red zone)
Air intake—FRESH (outside air)
Air flow—FLOOR
Air conditioning—OFF
For quick heating, select recirculated
air for a few minutes. To keep the
windows from fogging, select fresh af-
ter the vehicle interior has been
warmed.
Press the “A/C” button on for dehumidi-
fied heating.
Choose floor/windshield air flow to heat
the vehicle interior while defrosting or
defogging the windshield.
Air conditioning
For best results, set controls to:
Fan speed— Any setting except “OFF”
Temperature— To w a r d s COLD
(blue zone)
Air intake—FRESH (outside air)
Air flow—PANEL
Air conditioning—ON
For quick cooling, turning the temperature
selector knob fully towards COLD changes
the air intake selector mode to
RECIRCULATE. It is not possible to return
to FRESH and to turn the air conditioning
system off in this position.

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“AUTO” button
For automatic operation of the air condi-
tioning, press the “AUTO” button. An indi-
cator light will illuminate to show that the
automatic operation mode has been se-
lected.
In the automatic operation mode, the air
conditioning selects the most suitable fan
speed, air flow, air intake and on−off of
the air conditioning according to the tem-
perature.
When you adjust the temperature selector
button to maximum cooling, “LO” will ap-
pear on the display and the air intake
mode will be automatically changed to RE-
CIRCULATE.
You may use manual controls if you want
to select your own settings.
Fan speed selector
Push the “
” (increase) or “” (de-
crease) side of the button to adjust the
fan speed.
In the automatic operation mode, the fan
speed is adjusted automatically unless you
desire another fan speed mode. “SYNC” button
Push the button to change the mode of
the temperature setting.
With the indicator on—
Simultaneous tem-
perature setting
With the indicator off— Individual temper-
ature setting
With the indicator on, the rear air condi-
tioning is turned on. However, controls on
the rear control panel cannot be used. To
cancel this function, push the “SYNC” but-
ton.
For details about the rear air conditioning,
see “Rear automatic air conditioning sys-
tem” on page 362 in this Section.
Temperature selectors
To increase the temperature, press the
“
” side. To decrease it, press the “”
side.
“LO” appears when you adjust to maxi-
mum cooling, and “HI” appears when you
adjust to maximum warming.
—“TEMP” button
With the “SYNC” button indicator on—
This button changes the temperature on
the driver side, front passenger side and
rear passenger side simultaneously. This function will be cancelled when the
“PASS TEMP” or “REAR TEMP” button is
pushed.
With the “SYNC” button indicator
off—
This button changes the temperature
on the driver side only.
—“PASS TEMP” button
This button changes the temperature on
the front passenger side only.
—“REAR TEMP” button
This button changes the temperature on
the rear passenger side only when the
rear air conditioning is turned on.
For details about the rear air conditioning,
see “Rear automatic air conditioning sys-
tem” on page 362 in this Section.
The temperature display changes between
“  C” and “ F” when the unit of the outside
temperature display is changed. (For de-
tails, see “Multi −information display” on
page 370 in Section 1 −10.)
“OFF” button
Push the button to turn off the air condi-
tioning system.

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If following another vehicle on a dusty
road, or driving in windy and dusty
conditions, it is recommended that the
air intake selector be temporarily set to
RECIRCULATE, which will close off the
outside passage and prevent outside
air and dust from entering the vehicle
interior.A U T O M AT I C O P E R AT I O N
Press in the “AUTO” button.
Temperature— To the desired
temperature
MANUAL OPERATION
For best results, set controls to:
Heating
Fan speed— To the desired fan speed
Temperature— Towards high temperature
Air intake—FRESH (outside air)
Air flow—FLOOR
Air conditioning—OFF
For quick heating, select recirculated
air for a few minutes. To keep the
windows from fogging, select fresh af-
ter the vehicle interior has been
warmed.
Press the “A/C” button on for dehumidi-
fied heating.
Choose floor/windshield air flow to heat
the vehicle interior while defrosting or
defogging the windshield. Air conditioning
Fan speed— To the desired fan speed
Temperature— Towards low temperature
Air intake—FRESH (outside air)
Air flow—PANEL
Air conditioning—ON
For quick cooling, select recirculated
air for a few minutes.
Ventilation
Fan speed— To the desired fan speed
Temperature— To w a r d s low temperature
Air intake—FRESH (outside air)
Air flow—PANEL
Air conditioning—OFF

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“AUTO” button
For automatic operation of the rear air
conditioning, press the “AUTO” button. An
indicator light will illuminate to show that
the automatic operation mode has been
selected.
In the automatic operation mode, the air
conditioning selects the most suitable fan
speed and air flow according to the tem-
perature.
You may use manual controls if you want
to select your own settings.
Fan speed selectors
Push the button to select the fan speed
mode.
In the automatic operation mode, the fan
speed is adjusted automatically unless you
desire another fan speed mode.Temperature selectors
To increase the temperature, press the
“
 ” side. To decrease it, press the “ ”
side.
“LO” appears when you adjust to maxi-
mum cooling, and “HI” appears when you
adjust to maximum warming.
When “SYNC” appears on the rear tem-
perature display, rear controls cannot be
used. Use the controls on the front control
panel. To cancel this function, push the
“SYNC” button. For details about the
“SYNC” button, see “Front automatic air
conditioning system” on page 354 in this
Section.
The temperature display changes between
“  C” and “ F” when the unit of the outside
temperature display is changed. (For de-
tails, see “Multi −information display” on
page 370 in Section 1 −10.)
“REAR” button
To turn on the rear air conditioning system
using the front control panel, push the
button. To turn it off, push the button
again.
“OFF” button
Push the button to turn off the rear air
conditioning system.
Air flow selectors
Push the button to select the vents used
for air flow. 1. Panel— Air flows from the roof panel
vents.
2. Bilevel— Air flows from both the roof
panel vents and floor vent.
3. Floor— Air flows from the floor vent.

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Keep your engine in good running
order. Malfunctions in the engine
electrical system, electronic ignition
system/distributor ignition system
or fuel system could cause an ex-
tremely high threeway catalytic
converter temperature.
 If the engine becomes difficult to
start or stalls frequently, take your
vehicle in for a checkup as soon
as possible. Remember, your Toyota
dealer knows your vehicle and its
threeway catalytic converter sys-
tem best.
 To ensure that the threeway cata-
lytic converter and the entire emis-
sion control system operate proper-
ly, your vehicle must receive the
periodic inspections required by the
Toyota Maintenance Schedule. For
scheduled maintenance information,
refer to the “Scheduled Maintenance
Guide” or “Owner ’s Manual Supple-
ment”.CAUTION
Exhaust gases include harmful car-
bon monoxide (CO) that is colorless
and odorless. Inhaling exhaust
gases may lead to death or a seri-
ous health hazard.
The exhaust should be checked
occasionally. If there is a hole or
crack caused by corrosion, damage
to a joint or abnormal exhaust
noise, be sure to have the vehicle
inspected and repaired by your
Toyota dealer. Failure to do so may
allow exhaust gases to enter the
vehicle, resulting in death or a
serious health hazard.
If the vehicle is in a poorly venti-
lated area, turn the engine off. In
a closed area, such as a garage,
exhaust gases may collect and en-
ter the vehicle. This may lead to
death or a serious health hazard.
Do not remain for a long time in a
parked vehicle with the engine run-
ning. If it is unavoidable, however,
do so only in an unconfined area
and adjust the heating or cooling
system to force outside air into the
vehicle.
Keep the back door and quarter
windows closed while driving. An
open or unsealed back door and
quarter windows may cause exhaust
gases to be drawn into the vehicle.
To allow proper operation of your
vehicle’s ventilation system, keep
the inlet grilles in front of the wind-
shield clear of snow, leaves, or oth-
er obstructions.
If the smell of exhaust is noticed
inside the vehicle, open the win-
dows. Large amounts of exhaust in
the vehicle can cause driver drowsi-
ness and an accident, resulting in
death or a serious health hazard.
Have the vehicle inspected by your
Toyota dealer immediately.
Engine exhaust cautions

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Do not leave the engine running in
an area with snow buildup, or
where it is snowing. If snowbanks
build up around the vehicle while
the engine is running, exhaust
gases may collect and enter the ve-
hicle. This may lead to death or a
serious health hazard.
When taking a nap in the vehicle,
always turn the engine off. Other-
wise, you may accidentally move
the sift lever or depress the accel-
erator pedal, which could cause an
accident or fire due to engine over-
heating. Additionally, if the vehicle
is parked in a poorly ventilated
area, exhaust gases may collect and
enter the vehicle, leading to death
or a serious health hazard.
FUNCTIONS OF ENGINE OIL
Engine oil has the primary functions of
lubricating and cooling the inside of the
engine, and plays a major role in main-
taining the engine in proper working order.
ENGINE OIL CONSUMPTION
It is normal that an engine should con-
sume some engine oil during normal
engine operation. The causes of oil
consumption in a normal engine are as
follows.
Oil is used to lubricate pistons, piston
rings and cylinders. A thin film of oil
is left on the cylinder wall when a pis-
ton moves downwards in the cylinder.
High negative pressure generated when
the vehicle is decelerating sucks some
of this oil into the combustion chamber.
This oil as well as some part of the oil
film left on the cylinder wall is burned
by the high temperature combustion
gases during the combustion process.
Oil is also used to lubricate the stems
of the intake valves. Some of this oil
is sucked into the combustion chamber
together with the intake air and is
burned along with the fuel. High tem-
perature exhaust gases also burn the
oil used to lubricate the exhaust valve
stems.The amount of engine oil consumed de-
pends on the viscosity of the oil, the
quality of the oil and the conditions the
vehicle is driven under.
More oil is consumed by high
−speed driv-
ing and frequent acceleration and decel-
eration.
A new engine consumes more oil, since
its pistons, piston rings and cylinder walls
have not become conditioned.
Oil consumption: Max. 1.0 L per 1000
km (1.1 qt./600 miles, 0.9 Imp. qt./600
miles)
When judging the amount of oil con-
sumption, note that the oil may become
diluted and make it difficult to judge
the true level accurately.
As an example, if a vehicle is used for
repeated short trips, and consumes a nor-
mal amount of oil, the dipstick may not
show any drop in the oil level at all, even
after 1000 km (600 miles) or more. This
is because the oil is gradually becoming
diluted with fuel or moisture, making it
appear that the oil level has not changed.
The diluting ingredients evaporate out
when the vehicle is then driven at high
speeds, as on an express way, making it
appear that oil is excessively consumed
after driving at high speeds.
Facts about engine oil
consumption

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If your engine coolant temperature
gauge indicates overheating, if you ex-
perience a loss of power, or if you hear
a loud knocking or pinging noise, the
engine has probably overheated. You
should follow this procedure...1. Pull safely off the road, stop the ve- hicle and turn on your emergency
flashers. Put the transmission in “P”
and apply the parking brake. Turn off
the air conditioning if it is being used.
2. If coolant or steam is boiling out of the radiator or reservoir, stop the engine.
Wait until the steam subsides before
opening the hood. If there is no coolant
boiling over or steam, leave the engine
running and make sure the electric
cooling fan is operating. If it is not,
turn the engine switch off.
CAUTION
To help avoid personal injury, keep
the hood closed until there is no
steam. Escaping steam or coolant is
a sign of very high pressure.
3. Look for obvious coolant leaks from theradiator, hoses, and under the vehicle.
However, note that water draining from
the air conditioning is normal if it has
been used.
CAUTION
When the engine is running, keep
hands and clothing away from the
moving fan and engine drive belts.
4. If the coolant is leaking, stop the en-gine immediately. Call a Toyota dealer
for assistance.
5. If there are no obvious leaks, check the coolant reservoir. If it is dry, add
coolant to the reservoir while the en-
gine is running. Fill it about half full.
CAUTION
Do not attempt to remove the radiator
cap when the engine and radiator are
hot. Serious injury could result from
scalding hot fluid and steam blown
out under pressure.
6. After the engine coolant temperaturehas cooled to normal, again check the
coolant level in the reservoir. If neces-
sary, bring it up to half full again. Seri-
ous coolant loss indicates a leak in the
system. You s hould have it checked as
soon as possible at your Toyota dealer.
If your vehicle overheats