2021 TOYOTA TUNDRA cooling

3405-1. Using the air conditioning system
Manual air conditioning system
■Adjusting the temperature setting
To adjust the temperature set-
ting, turn the temperature con-
trol dial clockwise (warm) or
counterclockwise (cool).
If is not pressed, the
system will blow ambient tem-
perature air or heated air.
For quick cooling, turn the tem-
perature control dial to the “MAX
A/C” position.
The air conditioning will automatically turn on and the air int ake selector
will be set to recirculated air mode.
: If equipped
Air conditioning controls

4136-3. Do-it-yourself maintenance
6
Maintenance and care
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
● Keep hands, clothing and tools away from the moving fan and eng ine
drive belt.
● Be careful not to touch the engine, 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 or t he bat-
tery. Fuel and battery fumes are flammable.
● Be extremely cautious when working on the battery. It contains poisonous
and corrosive sulfuric acid.
■ When working near the electric cooling fan or radiator grille
Be sure the engine switch is off.
With the engine switch in ON, the electric cooling fan may auto matically
start to run if the air conditioning is on and/or the coolant temperature is
high. ( P. 420)
■ 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 engine wear
due to dirt in the air.

4156-3. Do-it-yourself maintenance
6
Maintenance and care
Engine compartment
Washer fluid tank (P. 425)
Engine oil level dipstick ( P. 416)
Engine coolant reservoir ( P. 418)
Engine oil filler cap ( P. 417)
Brake fluid reservoir ( P. 420) Fuse box (
P. 454)
Battery ( P. 422)
Radiator ( P. 420)
Cooling fan
Condenser ( P. 420)
Power steering fluid reservoir ( P. 421)1
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4196-3. Do-it-yourself maintenance
6
Maintenance and care
■Coolant selection
Only use “Toyota Super Long Life Coolant” or a similar high quality ethylene
glycol based non-silicate, non-amine, non-nitrite, and non-bora te coolant with
long-life hybrid organic acid technology.
U.S.A.:
“Toyota Super Long Life Coolant” is a mixture of 50% coolant and 50% deion-
ized water. (Minimum temperature: -31 F [-35 C])
Canada:
“Toyota Super Long Life Coolant” is a mixture of 55% coolant and 45% deion-
ized water. (Minimum temperature: -44 F [-42 C])
For more details about coolant, contact your Toyota dealer.
■ If the coolant level drops within a short time of replenishing
Visually check the radiator, hoses, engine coolant reservoir ca p, 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.
WARNING
■ When the engine is hot
Do not remove the radiator cap.( P. 531)
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.

5287-2. Steps to take in an emergency
NOTICE
■When handling jumper cables
When connecting the jumper cables, ensure that they do not beco me entan-
gled in the cooling fan or belt.

529
7
When trouble arises
7-2. Steps to take in an emergency
If your vehicle overheats
●The needle of the engine coolant temperature gauge ( P. 1 0 5 )
enters the red zone or a loss of engine power is experienced. ( For
example, the vehicle speed does not increase.)
● “ENGINE COOLANT OVERTEMP” is shown on the multi-informa-
tion display.
● Steam comes out f rom under the hood.
Stop the vehicle in a safe place and turn off the air condition ing sys-
tem, and then stop the engine.
If you see steam:
Carefully lift the hood after the steam subsides.
If you do not see steam:
Carefully lift the hood.
After the engine has cooled
down sufficiently, inspect the
hoses and radiator core (radia-
tor) for any leaks. Radiator
Cooling fan
If a large amount of coolant leaks,
immediately contact your Toyota
dealer.
The following may indicate that your vehicle is overheating:
Correction procedures
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3
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2

5307-2. Steps to take in an emergency
The coolant level is satisfactory
if it is between the “FULL” and
“LOW” lines on the reservoir.Reservoir
“FULL”
“LOW”
Radiator cap
Add coolant if necessary.
Water can be used in an emer-
gency if coolant is unavailable.
Start the engine to check that the radiator cooling fan operate s and
to check for coolant leaks from the radiator or hoses.
If the fan is not operating:
Stop the engine immediately and contact your Toyota dealer.
If the fan is operating:
Have the vehicle ins pected at the nearest Toyota dealer.
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5317-2. Steps to take in an emergency
7
When trouble arises
WARNING
■When inspecting under th e hood of your vehicle
Observe the following precautions.
Failure to do so may result in serious injury such as burns.
● If steam is seen coming from under the hood, do not open the ho od until
the steam has subsided. The engine compartment may be very hot.
● Keep hands and clothing away from the fans, etc., while the engine is run-
ning.
● Do not loosen the radiator cap and the coolant reservoir cap wh ile the
engine and radiator are hot.
High temperature steam or coolant could spray out.
NOTICE
■ When adding engine coolant
Add coolant slowly after the engine has cooled down sufficientl y. Adding
cool coolant to a hot engine too quickly can cause damage to th e engine.
■ To prevent damage to the cooling system
Observe the following precautions:
● Avoid contaminating the coolant with foreign matter (such as sa nd or dust,
etc.).
● Do not use any coolant additives.