2021 TOYOTA PRIUS cooling

871-4. Hybrid system
PRIUS_OM_OM47E09U_(U)
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For safety and security
■Sounds and vibrations sp ecific to a hybrid vehicle
There may be no engine sound or vibration even though the vehic le is able to
move with the “READY” indicator is illuminated. For safety, app ly the parking
brake and make sure to shift the shift position to P when parke d.
The following sounds or vibrations may occur when the hybrid sy stem is
operating and are not a malfunction:
● Motor sounds may be heard from the engine compartment.
● Sounds may be heard from the hybrid battery (traction battery) under the
rear seats when the hybrid system starts or stops.
● Relay operating sounds such as a snap or soft clank will be emi tted from the
hybrid battery (traction battery), under the rear seats, when the hybrid sys-
tem 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 driving 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. ( P. 89)
■ Vehicle proximity notification system
In the following cases, the vehicle proximity notification syst em may be diffi-
cult for surrounding people to hear.
● In very noisy areas
● In the wind or the rain
Also, as the vehicle proximity notification system is installed on the front of
the vehicle, it may be more difficult to hear from the rear of the vehicle com-
pared to the front.
■ When “Proximity Notification Syst em Malfunction Visit Your Dealer” is
displayed on the multi-information display
The vehicle proximity notification system may be malfunctioning . Have the
vehicle inspected by your Toyota dealer immediately.
■ Maintenance, repair, recycling, and disposal
Contact your Toyota dealer regarding maintenance, repair, recyc ling and dis-
posal. Do not dispose of the vehicle yourself.

891-4. Hybrid system
PRIUS_OM_OM47E09U_(U)
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For safety and security
There is an air intake vent under
the right side of the rear seat for
the purpose of cooling the hybrid
battery (traction battery). If the
vent is blocked, charging/dis-
charging of the hybrid battery
(traction battery) may become lim-
ited.
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 minimize the ri sk of electrocution and fuel leakage. If
the emergency shut off system activates, your vehicle will not restart.
To restart the hybrid system , contact your Toyota dealer.
A message is automatically displ ayed 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
instructions.
Hybrid battery (traction battery) air intake vent
Emergency shut off system
Hybrid warning message

941-4. Hybrid system
PRIUS_OM_OM47E09U_(U)
NOTICE
■Hybrid battery (traction battery) air intake vent
● Make sure not to block the air intake vent with anything, such as a seat
cover, plastic cover, or luggage. If the vent is blocked, the charging/dis-
charging of the hybrid battery (traction battery) may become li mited.
● When dust etc. has accumulated in the air intake vent, clean it with a vac-
uum cleaner to prevent the vent from clogging.
● Do not get water or foreign materials in the air intake vent as this may
cause a short circuit and damage the hybrid battery (traction b attery).
● Do not carry large amounts of water such as water cooler bottle s in the
vehicle. If water spills onto the hybrid battery (traction batt ery), the battery
may be damaged. Have the vehicle inspected by your Toyota deale r.
● There is a filter installed to the air intake vent. When the fi lter remains
noticeably dirty even after cleaning the air intake vent, filte r cleaning or
replacement is recommended. For information regarding filter cl eaning or
replacement, refer to P. 551.
● If “Maintenance required for Traction battery cooling parts See owner’s
manual” is shown on the multi-information display, the air intake vent and
filter may be clogged. Refer to P. 551 for information on how to clean the
air intake vent.

4385-1. Using the air conditioning system and defogger
PRIUS_OM_OM47E09U_(U)
Press .
Adjust the temperature setting. ( P. 4 3 6 )
Press .
The cooling and dehumidificati on function switches between on a nd
off each time is pressed.
To stop the operation, press .
■Automatic mode indicator
If the fan speed setting or air flow modes are operated, the
indicator goes off. However, automatic mode for functions other
than that operat ed is maintained.
This function automatically contro ls the air conditioning airflow so that
priority is given to the front seats. When the front passenger seat is
not occupied, airflow may switch to only the driver’s seat. Unn eces-
sary air conditioning is suppressed, contributing to increased fuel effi-
ciency.
Front seat concentrated airflow mode operates in the following situa-
tions.
● No passengers are dete cted in the rear seats
● The windshield defogger is not operating
While operating, illuminates.
Using automatic mode
Front seat concentrated airflow mode (S-FLOW)
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PRIUS_OM_OM47E09U_(U)
4435-1. Using the air conditioning system and defogger
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Interior features
■Fogging up of the windows
●The windows will easily fog up when the humidity in the vehicle is high.
Turning on will dehumidify the air from the outlets and defog the
windshield effectively.
● If you turn off, the windows may fog up more easily.
● The windows may fog up if the recirculated air mode is used.
■ When driving on dusty roads
Close all windows. If dust thrown up by the vehicle is still drawn into the vehi-
cle after closing the windows, it is recommended that the air intake mode be
set to outside air mode and the fan speed to any setting except off.
■ Outside/recirculated air mode
●Setting to the recirculated air mode temporarily is recommended in prevent-
ing dirty air from entering the vehicle interior and helping to cool the vehicle
when the outside air temperature is high.
● Outside/recirculated air mode may automatically switch dependin g on the
temperature setting or the inside temperature.
■ Fresh air intake system while parking
When parking, the system automatically switches to outside air mode to
encourage better air circulation throughout the vehicle, helpin g to reduce
odors that occur when starting the vehicle.
■ Operation of the air conditioning system in the air conditionin g eco
mode
● In the air conditioning eco mode, the air conditioning system i s controlled as
follows to prioritize fuel efficiency:
• Engine speed and compressor operation controlled to restrict h eating/
cooling capacity
• Fan speed restricted when automatic mode is selected
● To improve air conditioning performance, perform the following operations:
• Adjust the fan speed
• Adjust the temperature setting
• Turn off the air conditioning eco mode
● When the driving mode is set to Eco driving mode, the air condi tioning eco
mode will be turned on automatically. Even in this case, the ai r conditioning
eco mode can be turned off by pressing . ( P. 347)
■ When the outside tempera ture falls to nearly 32F (0 C)
The dehumidification function may not operate even when is pressed.

PRIUS_OM_OM47E09U_(U)
4535-1. Using the air conditioning system and defogger
5
Interior features
■Fogging up of the windows
●The windows will easily fog up when the humidity in the vehicle is high.
Turning on will dehumidify the air from the outlets and defog the
windshield effectively.
● If you turn off, the windows may fog up more easily.
● The windows may fog up if the recirculated air mode is used.
■ When driving on dusty roads
Close all windows. If dust thrown up by the vehicle is still drawn into the vehi-
cle after closing the windows, it is recommended that the air intake mode be
set to outside air mode and the fan speed to any setting except off.
■ Outside/recirculated air mode
●Setting to the recirculated air mode temporarily is recommended in prevent-
ing dirty air from entering the vehicle interior and helping to cool the vehicle
when the outside air temperature is high.
● Outside/recirculated air mode may automatically switch dependin g on the
temperature setting or the inside temperature.
■ Fresh air intake system while parking
When parking, the system automatically switches to outside air mode to
encourage better air circulation throughout the vehicle, helpin g to reduce
odors that occur when starting the vehicle.
■ Operation of the air conditioning system in the air conditionin g eco
mode
● In the air conditioning eco mode, the air conditioning system i s controlled as
follows to prioritize fuel efficiency:
• Engine speed and compressor operation controlled to restrict h eating/
cooling capacity
• Fan speed restricted when automatic mode is selected
● To improve air conditioning performance, perform the following operations:
• Adjust the fan speed
• Adjust the temperature setting
• Turn off the air conditioning eco mode
● When the driving mode is set to Eco driving mode, the air condi tioning eco
mode will be turned on automatically. Even in this case, the ai r conditioning
eco mode can be turned off by selecting . ( P. 347)
■ When the outside tempera ture falls to nearly 32F (0 C)
The dehumidification function may not operate even when is
selected.

PRIUS_OM_OM47E09U_(U)
5136-3. Do-it-yourself maintenance
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Maintenance and care
Tire inflation
pressure
( P. 542)• Tire pressure gauge
• Compressed air source
Washer fluid
( P. 5 3 0 )• Water or washer fluid containing antifreeze (for win-
ter use)
• Funnel (used only for adding water or washer fluid)
WARNING
The engine compartment contains many mechanisms and fluids that may
move suddenly, become hot, or become electrically energized. To avoid death
or serious injury, observe the following precautions.
■When working on the engine compartment
● Make sure that the “Accessory”, “Ignition ON” or mileage displa y
( P. 116) on the main display and the “READY” indicator are both off.
● Keep hands, clothing and tools away from the moving fan.
● Be careful not to touch the engine, power control unit, radiator, exhaust
manifold, etc. right after driving as they may be hot. Oil and other fluids
may also be hot.
● Do not leave anything that may burn easily, such as paper and r ags, in the
engine compartment.
● Do not smoke, cause sparks or expose an open flame to fuel. Fuel fumes
are flammable.
● Be extremely cautious when working on the 12-volt battery. It c ontains poi-
sonous and corrosive sulfuric acid.
■ When working near the electric cooling fans or radiator grille
Be sure the power switch is off.
With the power switch in ON mode, the electric cooling fans may automati-
cally start to run if the air conditioning is on and/or the coolant temperature
is high. ( P. 524)
■ Safety glasses
Wear safety glasses to prevent flying or falling material, fluid spray, etc.
from getting in your eyes.
ItemsParts and tools

518
PRIUS_OM_OM47E09U_(U)
6-3. Do-it-yourself maintenance
Engine compartment
Engine coolant reservoir ( P. 522)
Fuse boxes ( P. 563)
Engine oil level dipstick ( P. 519)
Engine oil filler cap ( P. 520)
Brake fluid reservoir ( P. 528) 12-volt battery (
P. 524)
Power control unit coolant
reservoir ( P. 522)
Radiator ( P. 524)
Condenser ( P. 524)
Electric cooling fans
Washer fluid tank ( P. 530)1
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