2020 TOYOTA MIRAI cooling

912. Fuel cell vehicle
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Fuel cell system
MIRAI_OM_USA_OM62073U
The fuel cell vehicle has high-voltage components (about 650 V m axi-
mum) such as a fuel cell stack, traction battery, power control unit,
high-voltage cables (which are di stinguished from low-voltage cables
by their orange covers), electric motor (traction motor), etc., and high-
temperature parts such as the radiator for cooling. Pay attenti on to all
warning labels attached to the vehicle.
This diagram is for illustrative purposes only and may differ f rom the
actual vehicle.
High-voltage and high-temperature components
Warning label
Power control unit
High-voltage cables (orange)
Fuel cell stack
Traction battery
Service plug
Fuel cell converter Electric motor (traction motor)
Air conditioning compressor
Radiator for inverter cooling
Radiator for fuel cell stack
cooling
Auxiliary inverter
Cabin coolant heater

932. Fuel cell vehicle
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Fuel cell system
MIRAI_OM_USA_OM62073U
There is an air intake vent beside
the rear left seat for the purpose
of cooling the traction battery. If
the air intake vent is blocked, it
could lead to a reduction in trac-
tion battery output.
■If a warning light comes on, a warning message is displayed, or the
12-volt battery connection is disconnected
The fuel cell system may not be able to restart.
If the “READY” indicator does not come on, even when the start procedure is
repeated, contact your Toyota dealer.
■ If “Hydrogen Leakage Detected Visit Your Dealer” is displayed on the
multi-information display
A small amount of hydrogen gas may be leaking. Have the vehicle inspected
immediately at the nearest Toyota dealer.
■ If “FC System Shutdown due to Hydrogen Leakage Stop Your Vehicle in
a Safe Place and Contact Your Dealer” is displayed on the multi -informa-
tion display
● Hydrogen gas may be leaking.
When hydrogen gas is leaking or some other malfunction is detected:
P. 98
● The air conditioning system will shut off automatically.
■ Running out of fuel
When the vehicle has run out of fuel and the fuel cell system c annot be
started, refuel the vehicle until the low fuel level warning li ght (P. 420) turns
off before trying to restart. It may not be able to restart if the refueled amount
is too low (less than about 2.7 lb. [1.2 kg]).
Traction battery air intake vent

3086-1. Using the air conditioning system and defogger
MIRAI_OM_USA_OM62073U
Touch .
The dehumidification function begi ns to operate. Air outlets and fan
speed are automatically adjusted according to the temperature s et-
ting.
Adjust the temperature setting.
Touch .
The cooling and dehumidificati on function switches between on a nd
off each time is touched.
To stop the operation, touch .
■Automatic mode indicator
If the fan speed setting or air flow modes are operated, the au to-
matic mode indicator goes off. However, automatic mode for func -
tions other than that o perated are maintained.
■Switching between outside air and recirculated air modes
Press .
The mode switches between outside air mode (indicator off) and recir-
culated air mode (indicator on) each time is pressed.
■
Using the ECO HEAT/COOL mode
Touch .
is displayed on the air conditioning screen, and the air condi tion-
ing is controlled with low fuel consumption prioritized. When is
touched and held, is displayed on the screen, and the air cond i-
tioning is controlled, even more, with low fuel consumption pri oritized.
(The air conditioning will have more reserved operation.)
When canceling ECO HEAT/COOL mode, touch the again.
may be canceled when other air conditioning operation switches
are touched.
Using the automatic air conditioning system
Other functions
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3116-1. Using the air conditioning system and defogger
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Interior features
MIRAI_OM_USA_OM62073U■
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 wind-
shield effectively.
● If you turn off, the windows may fog up more easily.
● The windows may fog up if the recirculated air mode is used.
■ Windshield fog detection function
When automatic mode is set, the humidity sensor (P. 314) detects fog on
the windshield and controls the air conditioning system to prev ent fog.
■ Outside/recirculated air mode
●When driving on dusty roads such as tunnels or in heavy traffic, set the out-
side/recirculated air mode button to recirculated air mode. Thi s is effective in
preventing outside air from entering the vehicle interior. Duri ng cooling oper-
ation, setting the recirculated air mode will also cool the vehicle interior
effectively.
● Outside/recirculated air mode may automatically switch dependin g on the
temperature setting or the inside temperature.
■ Operation of the air conditioni ng system in ECO HEAT/COOL mode
● In ECO HEAT/COOL mode, the air conditioning system is controlle d as fol-
lows to prioritize fuel efficiency:
• Fluid (heating) heater and compressor operation controlled to restrict
heating/cooling capacity
• Fan speed restricted when automatic mode is selected
● To improve air conditioning performance, perform the following operations:
• Adjust the temperature settings and fan speed
• Touch while in , and is set
• Touch while in , and ECO HEAT/COOL mode is canceled
■ Operation of the air conditioning system in Eco drive mode
When “ECO MODE” switch is pressed, operations switch over to EC O HEAT/
COOL mode. ( P. 197)
■ When the outside temperature exceeds 75°F (24°C) and the air co ndition-
ing system is on
● In order to reduce the air conditioning power consumption, the air condition-
ing system may switch to recirculated air mode automatically. This may also
reduce fuel consumption.
● Recirculated air mode is selected as a default mode when the power switch
is turned to ON mode.
● It is possible to switch to outside air mode at any time by pre ssing .

3657-3. Do-it-yourself maintenance
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Maintenance and care
WARNING
The motor 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 motor compartment
● Be careful not to touch the high-voltage parts or hydrogen-rela ted parts.
● Make sure that the “READY” indicator is off.
● Keep hands, clothing and tools away from the moving fans.
● Be careful not to touch the motor, inverter, radiator, etc., ri ght after driving
as they may be hot. Coolant and other fluids may also be hot.
● Do not leave anything that may burn easily, such as paper and r ags, in the
motor compartment.
● Do not smoke, cause sparks or expose an open flame to the 12-volt bat-
tery. 12-volt battery fumes are flammable.
● Be extremely cautious when working on the 12-volt battery. It c ontains poi-
sonous and corrosive sulfuric acid.
● Never touch, disassemble, remove or replace the high-voltage parts,
cables and their connectors. It can cause severe burns or electric shock
that may result in death or serious injury.
■ 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. 371)
■ Safety glasses
Wear safety glasses to prevent flying or falling material, fluid spray, etc.,
from getting in your eyes.
NOTICE
■If you remove the air cleaner filter
Driving with the air cleaner filter removed may cause excessive motor wear
due to dirt in the air.

3697-3. Do-it-yourself maintenance
MIRAI_OM_USA_OM62073U
7
Maintenance and care
Motor compartment
Washer fluid tank (P. 373)
Brake fluid reservoir ( P. 372)
Inverter coolant reservoir ( P. 370)
Fuse box ( P. 402)
Fuel cell stack coolant radiator
( P. 371) Inverter coolant radiator
( P. 371)
Condenser ( P. 371)
Electric cooling fans
Fuel cell stack coolant reser-
voir ( P. 370)
Fuel cell stack coolant sub
radiator ( P. 371)

3717-3. Do-it-yourself maintenance
MIRAI_OM_USA_OM62073U
7
Maintenance and care
■If the inverter coolant level drops within a short time of repl enishing
Visually check the radiators, hoses, inverter coolant reservoir cap, drain cock
and water pump.
If you cannot find a leak, have your Toyota dealer test the cap and check for
leaks in the cooling system.
Check the radiator and condenser and clear away any foreign objects.
If either of the above parts is extremely dirty or you are not sure of
their condition, have your vehic le inspected by your Toyota dea ler.
WARNING
■When the fuel cell system is hot
Do not remove the coolant reservoir caps.
The cooling system may be under pressure and may spray hot coolant if the
cap is removed, causing serious injuries, such as burns.
NOTICE
■When adding coolant
Coolant is neither plain water nor straight antifreeze. The cor rect mixture of
water and antifreeze must be used to provide proper lubrication , corrosion
protection and cooling. Be sure to read the antifreeze or coolant label.
■ If you spill coolant
Be sure to wash it off with water to prevent it from damaging p arts or paint.
Radiator and condenser
WARNING
■When the fuel cell system is hot
Do not touch the radiator or condenser as they may be hot and c ause seri-
ous injuries, such as burns.

4288-2. Steps to take in an emergency
MIRAI_OM_USA_OM62073U■
If “High FC Temperature Reduced Power” is displayed
Lower the speed while check the safety, and run the vehicle like this for
several minutes.
If the message goes off, the vehicle can be driven as is, since it temporarily
overheated.
This message may be displayed when driving under severe operati ng con-
ditions.
(For example, when driving up a long steep hill.)
■ If “FC System Shutdown due to F reezing conditions Stop Your Veh icle in
a Safe Place and Contact Your Dealer” is displayed.
P. 189
■ If “Maintenance Required for Hybrid Battery Cooling Parts at Yo ur
Dealer” is displayed
The filter may be clogged, the air intake vent may be blocked or there may be
a gap in the duct. Have maintenance performed on the traction b attery cool-
ing component at your Toyota dealer.
■ If “Shift to P Before Exiting Vehicle” is displayed
Message is displayed when the driver’s door is opened without t urning the
power switch to off with the shift position in any position oth er than P.
Shift the shift position to P.
■ If “Shift is in N Release Accelerator Before Shifting” is displ ayed
Message is displayed when the accelerator pedal has been depressed and
the shift position is in N. Release the accelerator pedal and s hift the shift posi-
tion to D or R.
■ If “Press Brake When Vehicle is Stopped FC System may Overheat” is
displayed
Message is displayed when the accelerator pedal is depressed to maintain
the vehicle position when stopped on an upward slope, etc.
If this continues, the fuel cell system may overheat.
Release the accelerator pedal and depress the brake pedal.
■ If “Accelerator Pedal is Pressed Check The Accelerator Pedal” i s dis-
played
The accelerator pedal may be stuck.
If the message does not disappear even when the foot has been removed
from the accelerator pedal, check that the accelerator pedal is not stuck.
■ If “Ion Filter Maintenance Requi red Visit Your Dealer” is displayed
Ion filter replacement is necessary. Contact your Toyota dealer .
■ If “Shift System Malfunction St op Your Vehicle in a Safe Place then See
Owner’s Manual” is displayed
The shift position may not be able to be shifted. Stop the vehi cle in a safe
place.
Contact your Toyota dealer immediately.
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