2021 TOYOTA SIENNA HYBRID cooling

811-4. Hybrid system
1
For safety and security
hybrid system, contact your Toyota
dealer.
■Charging the 12-volt battery
 P.508
■After the 12-volt battery has dis-
charged or when the terminal
has been removed and installed
during exchange, etc.
The gasoline engine may not stop
even if the vehicle is being driven by
the hybrid battery (traction battery).
If this continues for a few days, con-
tact your To yota dealer.
■Sounds and vibrations specific
to a hybrid vehicle
There may be no engine sound or
vibration even though the vehicle is
able to move with the “READY” indi-
cator is illuminate d. For safety,
make sure to shift the shift lever to P
and apply the parking brake when
parked.
The following sounds or vibrations
may occur when the hybrid system
is operating and are not a malfunc-
tion:
●Motor sounds may be heard from
the engine compartment.
●Sounds may be heard from the
hybrid battery (traction battery)
under the front seats when the
hybrid system starts or stops.
●Relay operating sounds such as a
snap or soft clank will be emitted
from the hybrid battery (traction
battery), under the front seats,
when the hybrid system is started
or stopped.
●Sounds from the hybrid system
may be heard when the back door
is open.
●Sounds may be heard from the
transmission when the gasoline
engine starts or stops, when driv-
ing at low speeds, or during idling.
●Engine sounds may be heard
when accelerating sharply.
●Sounds may be heard due to regenerative braking when the
brake pedal is depressed or as
the accelerator pedal is released.
●Vibration may be felt when the
gasoline engine starts or stops.
●Cooling fan sounds may be heard
from the air intake vent under the
front seat.
■Maintenance, repair, recycling,
and disposal
Contact your Toyota dealer regard-
ing maintenance, repair, recycling
and disposal. Do n ot dispose of the
vehicle yourself.
When driving with the gasoline
engine stopped, a sound, which
changes in accordance with the
driving speed, will be played in
order to warn people nearby of
the vehicle’s approach. The
sound will stop when the vehicle
speed exceeds approximately
22 mph (35 km/h).
■Acoustic Vehicle Alerting Sys-
tem
In the following cases, the Acoustic
Vehicle Alerting System may be dif-
ficult for surrounding people to hear.
●In very noisy areas
●In the wind or the rain
■If “Acoustic Vehicle Alerting
System Malfunction Visit Your
Dealer” is displayed on the
multi-information display
The system may be malfunctioning.
Have the vehicle inspected by your
Toyota dealer.
Acoustic Vehicle Alerting
System

851-4. Hybrid system
1
For safety and security
There are air intake vents under
the front seats for the purpose of
cooling the hybrid battery (trac-
tion battery). If the vent
becomes blocked, the hybrid
battery (traction battery) may
overheat, leading to a reduction
in hybrid battery (traction bat-
tery) output.
WARNING
●If a fire occurs in the hybrid
vehicle, leave the vehicle as
soon as possible. Never use a
fire extinguisher that is not
meant for electric fires. Using
even a small amount of water
may be dangerous.
●If your vehicle needs to be
towed, do so with four wheels
raised. If the wheels connected
to the electric motor (traction
motor) are on the ground when
towing, the motor may continue
to generate electricity. This may
cause a fire. ( P.462)
●Carefully inspect the ground
under the vehicle. If you find
that liquid has leaked onto the
ground, the fuel system may
have been damaged. Leave the
vehicle as soon as possible.
■Hybrid battery (traction bat-
tery)
●Never resell, hand over or mod-
ify the hybrid battery. To prevent
accidents, hybrid batteries that
have been removed from a dis-
posed vehicle are collected
through Toyota dealer. Do not
dispose of the battery yourself.
Unless the battery is properly col-
lected, the follo wing may occur,
resulting in dea th or serious
injury:
• The hybrid battery may be ille- gally disposed of or dumped,
and it is hazardous to the envi-
ronment or someone may touch
a high voltage part, resulting in
an electric shock.
• The hybrid battery is intended to be used exclusively with your
hybrid vehicle. If the hybrid bat-
tery is used out side of your
vehicle or modified in any way,
accidents such as electric
shock, heat generation, smoke
generation, an explosion and
electrolyte leakage may occur.
When reselling or handing over
your vehicle, the possibility of an
accident is extremely high
because the person receiving the
vehicle may not be aware of these
dangers.
●If your vehicle is disposed of
without the hybrid battery hav-
ing been removed, there is a
danger of serious electric shock
if high voltage parts, cables and
their connectors are touched. In
the event that your vehicle must
be disposed of, the hybrid bat-
tery must be disposed of by
your Toyota dealer or a qualified
service shop. If the hybrid bat-
tery is not disposed of properly,
it may cause electric shock that
can result in dea th or serious
injury.
Hybrid battery (traction
battery) air intake vents

861-4. Hybrid system
When a certain level of impact is
detected by the impact sensor,
the emergency shut off system
blocks the high voltage current
and stops the fuel pump to mini-
mize the risk of electrocution
and fuel leakage. If the emer-
gency shut off system activates,
your vehicle will not restart. To
restart the hybrid system, con-
tact your Toyota dealer.
A message is automatically dis-
played when a malfunction
occurs in the hybrid system or
an improper operation is
attempted.
If a warning message is shown
on the multi-information display,
read the message and follow the
NOTICE
■Hybrid battery (traction bat-
tery) air intake vents
●Make sure not to block the air
intake vents with anything, such
as a seat cover, plastic cover, or
luggage. If the vents become
blocked, the hybrid battery
(traction battery) input and out-
put may be restricted, leading to
a reduction in hybrid battery
(traction battery) output and a
malfunction.
●When dust etc. has accumu-
lated in the air intake vents,
clean them with a vacuum
cleaner to prevent the vents
from clogging.
●Do not get water or foreign
materials in the air intake vents
as this may cause a short circuit
and damage the hybrid battery
(traction battery).
●Do not carry large amounts of
water such as water cooler bot-
tles in the vehicle. If water spills
onto the hybrid battery (traction
battery), the battery may be
damaged. Have the vehicle
inspected by your Toyota
dealer.
●There are filters installed to the
air intake vents. When the filters
remain noticeably dirty even
after cleaning the air intake
vents, filters cleaning or
replacement is recommended.
For information regarding filters
cleaning or replacement, refer
to P.444.
●If “Maintenance Required for
Traction Battery Cooling Parts
See Owner’s Manual” is shown
on the multi-information dis-
play, the air intake vents and fil-
ters may be clogged. Refer to
P.443for information on how to
clean the air intake vents.
Emergency shut off sys-
tem
Hybrid warning message

3344-5. Using the driving support systems
driving.
2Sport mode
Controls the hybrid system to pro-
vide quick, powerful acceleration.
This mode also changes the steer-
ing feel, making it suitable for when
agile driving response is desired,
such as when driving on roads with
many curves.
When Sport mode is selected,
Sport mode indicator comes on.
3Eco drive mode
Helps the driver a ccelerate in an
eco-friendly manner and improve
fuel economy through moderate
throttle characteri stics and by con-
trolling the operation of the air con-
ditioning system (heating/cooling).
When Eco drive mode is selected,
Eco drive mode indicator comes
on.
■When changing to a driving
mode other than normal mode
●The background color of the multi-
information display changes
according to the selected driving
mode.
●When the speedometer is set to
analog display, the speedometer
display color also changes. (For
vehicles with the 7-inch multi-
information display only)
■Air conditioning system opera-
tion in Eco drive mode
In Eco drive mode, heating/cooling
operations and the fan speed is con-
trolled to improve fuel efficiency.
Perform the following procedures to
increase the air conditioning perfor-
mance.
●Turn eco air conditioning mode off
(  P.350)
●Adjust the fan speed ( P.349)
●Cancel Eco drive mode
■Canceling a driving mode
●Sport mode is automatically can-
celed and the driving mode
returns to normal mode when the
power switch is turned off.
●Normal mode and Eco drive mode
are not canceled until another
driving mode is selected. (Even if
the power switch is turned off, nor-
mal mode and Eco drive mode will
not be automatically canceled).

3414-6. Driving tips
4
Driving
4-6.Driving tips
When using Eco drive mode, the
torque corresponding to the
accelerator pedal depression
amount can be generated more
smoothly than it is in normal
conditions. In addition, the oper-
ation of the air conditioning sys-
tem (heating/cooling) will be
minimized, improving the fuel
economy. (P.333)
The Eco-friendly driving is pos-
sible by keeping the indicator of
Hybrid System Indicator within
Eco area. ( P.98, 102)
Shift the shift lever to D when
stopped at a traffic light, or driv-
ing in heavy traffic etc. Shift the
shift lever to P when parking.
When using the N position,
there is no positive effect on fuel
consumption. In the N position,
the gasoline engine operates but electricity cannot be gener-
ated. Also, when using the air
conditioning system, etc., the
hybrid battery (traction battery)
power is consumed.

Drive your vehicle smoothly.
Avoid abrupt acceleration and
deceleration. Gradual accel-
eration and deceleration will
make more effective use of
the electric motor (traction
motor) without having to use
gasoline engine power.
 Avoid repeated acceleration.
Repeated acceleration con-
sumes hybrid battery (trac-
tion battery) power, resulting
in poor fuel consumption. Bat-
tery power can be restored by
driving with the accelerator
pedal slightly released.
Make sure to operate the brakes
gently and in a timely manner. A
greater amount of electrical
energy can be regenerated
when slowing down.
Repeated acceleration and
deceleration, as well as long
waits at traffic lights, will lead to
bad fuel economy. Check traffic
Hybrid vehicle driving
tips
For economical and ecolog-
ical driving, pay attention to
the following points:
Using Eco drive mode
Use of Hybrid System
Indicator
Changing the shift posi-
tion
Accelerator pedal/brake
pedal operation
When braking
Delays

3495-1. Using the air conditioning system and defogger
5
Interior features
The air conditioning system
switches between individual and
synchronous modes each time the
“SYNC” switch is operated.
(  P.355)
■Setting the fan speed
Operate the fan speed control
switch upwards to increase the
fan speed and downwards to
decrease the fan speed.
Pressing the “OFF” switch turns off
the fan.
■Change the airflow mode
Operate the airflow mode con-
trol switch.
The airflow mode changes as fol-
lows each time the switch is oper-
ated.
1 Upper body
2 Upper body and feet
3 Feet
4 Feet and the windshield
defogger operates
■Switching between outside
air and recirculated air
modes
Press the outside/recirculated
air mode switch.
The mode switches between out-
side air mode and recirculated air
mode each time the switch is oper-
ated.
When recirculated air mode is
selected, the indicator illuminates
on the outside/recirculated air
mode switch.
■Set cooling and dehumidifi-
cation function
Press the “A/C” switch.
When the function is on, the “A/C
ON” display on the front air condi-
tioning operation panel appears.
■Defogging the windshield
Defoggers are used to defog the
windshield and front side win-
dows.
Press the windshield defogger
switch.
Set the outside/recirculated air
mode switch to outside air mode if
the recirculated air mode is used. (It
may switch automatically.)
To defog the windshield and the
side windows quickly, turn the air
flow and temperature up.
To return to the previous mode,
press the windshield defogger
switch again when the windshield is
defogged.
When the windshield defogger
switch is on, the indicator illumi-
nates on the windshield defogger

3515-1. Using the air conditioning system and defogger
5
Interior features
switch.
■Operation of the air condition-
ing system in Eco drive mode
●In Eco drive mode, the air condi-
tioning system is controlled as fol-
lows to prioritize fuel efficiency:
• Engine speed and compressor operation controlled to restrict
heating/cooling capacity
• Fan speed restr icted when auto-
matic mode is selected
●To improve air conditioning perfor-
mance, perform the following
operations:
• Adjust the fan speed
• Turn off Eco drive mode ( P.333)
• Turn off Eco air conditioning mode
●When the driving mode is set to
Eco driving mode, the Eco air con-
ditioning mode will be turned on
automatically. Even in this case,
the Eco air conditioning mode can
be turned off by pressing the Eco
air conditioning mode switch.
■When the outside temperature
falls to nearly 32°F (0°C)
The dehumidification function may
not operate even when “A/C” switch
is pressed.
■Ventilation and air conditioning
odors
●To let fresh air in, set the air condi-
tioning system to the outside air
mode.
●During use, various odors from
inside and outside the vehicle may
enter into and a ccumulate in the
air conditioning system. This may
then cause odor to be emitted
from the vents.
●To reduce potential odors from
occurring:
• It is recommended that the air conditioning system be set to out-
side air mode prior to turning the
vehicle off.
• The start timing of the blower may
be delayed for a short period of
time immediately after the air con-
ditioning system is started in auto- matic mode.
●When parking, the system auto-
matically switches to outside air
mode to encourage better air cir-
culation throughout the vehicle,
helping to reduce odors that occur
when starting the vehicle.
■Air conditioning filter
 P.441
■Air conditioning system refrig-
erant
●A label regarding the refrigerant of
the air conditioning system is
attached to the h ood at the loca-
tion shown in the following illustra-
tion.
●The meaning of each symbol on
the label are as follows:
■Customization
Some functions can be customized.
Caution
Air conditioning sys-
tem
Air conditioning sys-
tem lubricant type
Requires registered
technician to service
air conditioning sys-
tem
Flammable refrigerant

3525-1. Using the air conditioning system and defogger
(Customizable features: P.551)
■Main control screen
Adjust the left side seat tem-
perature setting
Adjust the fan speed setting
Select the air flow mode
: Air flows to the upper body
: Air flows to the upper body and
feet
: Air flows to the feet
: Air flows to the feet and the
windshield defogger operates
Adjust the right side seat
temperature setting
Display the option control
screen. ( P.353)
“AUTO” switch (automatic
mode)
Set automatic mode on/off
(  P.353)
“OFF” switch
Turn the fan off
Set cooling and dehumidifi-
cation function
If “A/C” switch is not pressed, the
WARNING
■To prevent the windshield
from fogging up
Do not use the windshield defog-
ger switch during cool air opera-
tion in extremely humid weather.
The difference between the tem-
perature of the outside air and
that of the windshield can cause
the outer surface of the wind-
shield to fog up, blocking your
vision.
■To prevent burns
●Vehicles with outside rear view
mirror defoggers: Do not touch
the outside rear view mirror sur-
faces, as they can become very
hot and burn you.
●Vehicles with windshield wiper
deicer: Do not touch the glass at
lower part of the windshield or
to the side of the front pillars
when the windshield wiper de-
icer is on.
NOTICE
■To prevent 12-volt battery dis-
charge
Do not leave the air conditioning
system on longer than necessary
when the hybrid system is off.
■When repairing/replacing
parts of the air conditioning
system
Have repair/replacement per-
formed by your Toyota dealer.
When a part of th e air condition-
ing system, such as the evapora-
tor, is to be replaced, it must be
replaced with a new one.
Front air conditioning
control screen
A
B
C
D
E
F
G
H