2017 TOYOTA MIRAI fc cooling

832. Fuel cell vehicle
2
Fuel cell system
MIRAI_OM_USA_OM62023U
The fuel cell vehicle has high-voltage components (about 650 V maxi-
mum) such as a fuel cell stack, traction battery, power control unit,
high-voltage cables (which are distinguished from low-voltage cables
by their orange covers), electric motor (traction motor), etc., and high-
temperature parts such as the radiator for cooling. Pay attention to all
warning labels attached to the vehicle.
This diagram is for illust rative purposes only and may differ from 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

852. Fuel cell vehicle
2
Fuel cell system
MIRAI_OM_USA_OM62023U
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 warn ing 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 pro\
cedure 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. 9 0
● 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 cannot be
started, refuel the vehicle until the low fuel level warning light ( →P. 371) 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

872. Fuel cell vehicle
2
Fuel cell system
MIRAI_OM_USA_OM62023U■
Fuel cell stack coolant
●Fuel cell stack coolant uses a specifically-designed fluid with high electrical
insulation properties, in order to safely cool the high-voltage fuel cell stack.
● Never add water or other coolants to the fuel cell stack cooling system, as
they will cause permanent damage.
● Consult your Toyota dealer for repleni shing or changing the fuel cell stack
coolant.
■ Ion filter
●An ion filter is installed in the coolant lines for the fuel cell stack, in order to
maintain the normal insulation properties of the coolant.
● It is necessary to periodically change the ion filter. ( →P. 378) Contact your
Toyota dealer for this periodic maintenance.
■ Tailpipe
●When the power switch is turned off and the fuel cell system is stopped
(→P. 173) after driving, exhaust water is discharged. Be careful when stand-
ing behind the vehicle to avoid dripping or spraying.
● It is possible to manually purge the exhaust. This may be desirable, for
instance, before parking in a garage. This is done by pressing the H
2O
switch. ( →P. 173)
● On cold days, water vapor in the exhaust may appear as a white mist emit-
ted from the tailpipe. This is not a malfunction.
● If the tailpipe is blocked, the fuel cell system will stop.
■ Hydrogen detectors
When the power switch is turned to ON mode, the hydrogen detectors are
activated.

2606-1. Using the air conditioning system and defogger
MIRAI_OM_USA_OM62023U
Touch .
The dehumidification function begins to operate. Air outlets and fan
speed are automatically adjusted according to the temperature set-
ting.
Adjust the temperature setting.
Touch .
The cooling and dehumidification function switches between on and
off each time the button is touched.
To stop the operation, touch .
■Automatic mode indicator
If the fan speed setting or air fl ow modes are operated, the auto-
matic mode indicator goes off. However, automatic mode for func-
tions other than that operated 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 condition-
ing is controlled with low fuel consumption prioritized. When is
touched and held, is displayed on the screen, and the air condi-
tioning is controlled, even more, with low fuel consumption prioritized.
(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
1
2
3
4

2636-1. Using the air conditioning system and defogger
6
Interior features
MIRAI_OM_USA_OM62023U■
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. 266) detects fog on
the windshield and controls the air conditioning system to prevent 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. This is effective in
preventing outside air from entering the vehicle interior. During cooling oper-
ation, setting the recirculated air mode will also cool the vehicle interior
effectively.
● Outside/recirculated air mode may automatically switch depending 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 controlled 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 conditio ning system in Eco drive mode
When ECO MODE switch is pressed, oper ations switch over to ECO HEAT/
COOL mode. ( →P. 183)
■ When the outside temperature exceeds 75°F (24°C) and the air condition-
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 pressing .

3197-3. Do-it-yourself maintenance
MIRAI_OM_USA_OM62023U
7
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-related 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., right 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 rags, 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 contains poi-
sonous and corrosive sulfuric acid.
● Take care because brake fluid can harm your hands or eyes and damage
painted surfaces. If fluid gets on your hands or in your eyes, flush the
affected area with clean water immediately.
If you still experience discomfort, consult a doctor.
● 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, t he electric cooling fans may automati-
cally start to run if the air conditioning is on and/or the coolant temperature
is high. ( →P. 325)
■ 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.

3237-3. Do-it-yourself maintenance
MIRAI_OM_USA_OM62023U
7
Maintenance and care
Motor compartment
Washer fluid tank (→P. 327)
Brake fluid reservoir (→ P. 326)
Inverter coolant reservoir (→ P. 324)
Fuse boxes ( →P. 355)
Fuel cell stack coolant radiator (→ P. 325) Inverter coolant radiator
(→ P. 325)
Condenser ( →P. 325)
Electric cooling fans
Fuel cell stack coolant reser-
voir ( →P. 324)
Fuel cell stack coolant sub
radiator ( →P. 325)

3257-3. Do-it-yourself maintenance
MIRAI_OM_USA_OM62023U
7
Maintenance and care
■If the inverter coolant level drops within a short time of replenishing
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 ex tremely dirty or you are not sure of
their condition, have your vehicle inspected by your Toyota dealer.
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 stra ight antifreeze. The correct 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 parts 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 cause seri\
-
ous injuries, such as burns.