2019 LEXUS RX450H cooling

5196-2. Using the air conditioning system and defogger
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Interior features
■When the outside temperature exceeds 75 F (24 C) and the air conditioning system
is on
●In order to reduce the air co nditioning power consumption, the air conditioning 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 the outside/recircu-
lated air mode button.
■Automatic mode for air intake control
In automatic mode, the system detects exhaust gas and other pollutants and automati-
cally switches between outside air and recirculated air modes.
When the dehumidification function is off, and the fan is operating, turning automatic
mode on will activate the dehumidification function.
■Fogging up of the windows
●The windows will easily fog up when the humidity in the vehicle is high. Selecting “A/C”
will dehumidify the air from the outlets and defog the windshield effectively.
●If you turn “A/C” 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. 521) detects fog on the wind-
shield and controls the air cond itioning system to prevent fog.
■Outside/recirculated air mode
●When driving on dusty roads such as tunnels or in heavy traffic, set the outside/recircu-
lated air mode button to the recirculated air mode. This is effective in preventing out-
side air from enteri ng the vehicle interior. During cooling operation, setting the
recirculated air mode will also cool the vehicle interior effectively.
●Outside/recirculated air mode may automa tically switch depending on the tempera-
ture setting or the inside temperature.
■When the outside temperature is low
The dehumidification function may not operate even when “A/C” is selected.
■Operation of the air conditioning system in Eco drive mode
●In the Eco drive mode, the air conditioning sy stem is controlled as follows to prioritize
fuel efficiency
• Engine speed 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 fan speed
• Turn off Eco drive mode

5947-3. Do-it-yourself maintenance
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*: Vehicles with sing le-beam headlights
Washer fluid
( P. 604)• Water or washer fluid containing antifreeze (for winter use)
• Funnel (used only for adding water or washer fluid)
WARNING
The engine compartment contains many mechan isms and fluids that may move suddenly,
become hot, or become electrically energize d. To avoid death or serious injury, observe
the following precautions.
■When working on the engine compartment
●Make sure that the “ACCESSORY” or “I GNITION ON” on the multi-information
display and the “READY” indicator are both off.
●Keep hands, clothing and tools away from the moving fan and engine drive belt.
●Be careful not to touch the engine, power co ntrol 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 rags, in the engine
compartment.
●Do not smoke, cause sparks or expose an open flame to fuel. Fuel fumes are flamma-
ble.
■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 automatically start to
run if the air conditioning is on and/ or the coolant temperature is high. ( P. 602)
■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 f ilter removed may cause excessive engine wear due to dirt
in the air.
ItemsParts and tools

5977-3. Do-it-yourself maintenance
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Maintenance and care
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■12-volt battery
P. 605
Engine compartment
Washer fluid tank ( P. 604)
Brake fluid reservoir ( P. 603)
Engine oil level dipstick (P. 598)
Engine coolant reservoir (P. 601)
Power control unit coolant reservoir ( P. 601) Fuse boxes (
P. 632)
Radiator ( P. 602)
Power control unit coolant
radiator ( P. 602)
Condenser ( P. 602)
Electric cooling fans
Engine oil filler cap ( P. 599)1
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6017-3. Do-it-yourself maintenance
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Maintenance and care
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The coolant level is satisfactory if it is between the “FULL” and “LOW” lines on
the reservoir when the hybrid system is cold.
■Engine coolant reservoir
Reservoir cap
“FULL” line
“LOW” line
If the level is on or below the “LOW”
line, add coolant up to the “FULL”
line. ( P. 702)
■Power control unit coolant reservoir
Reservoir cap
“FULL” line
“LOW” line
If the level is on or below the “LOW”
line, add coolant up to the “FULL”
line. ( P. 702)
■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-borate coolant with long-life hybrid
organic acid technology.
U.S.A.:
“Toyota Super Long Life Coolant” is a mixt ure of 50% coolant and 50% deionized water.
(Minimum temperature: -31 F [-35 C])
Canada:
“Toyota Super Long Life Cool ant” is a mixture of 55% coolant and 45% deionized water.
(Minimum temperature: -44 F [-42C])
For more details about coolant, contact your Lexus dealer.
■If the coolant level drops within a short time of replenishing
Visually check the radiator, hoses, engine/power control unit coolant reservoir caps,
drain cock and water pump.
If you cannot find a leak, have your Lexus de aler test the cap and check for leaks in the
cooling system.
Coolant
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6027-3. Do-it-yourself maintenance
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Check the radiator and condenser an d clear away any foreign objects.
If either of the above parts is extremely dirty or you are not sure of their condi-
tion, have your vehicle inspected by your Lexus dealer.
WARNING
■When the hybrid system is hot
Do not remove the engine/power control unit coolant reservoir caps and radiator cap.
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 correct mixture of water and
antifreeze must be used to provide proper lubrication, corrosion protection and cool-
ing. 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 hybrid system is hot
Do not touch the radiator or condenser as they may be hot and cause serious injuries,
such as burns.

7018-2. Steps to take in an emergency
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When trouble arises
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NOTICE
■When handling jumper cables
When connecting the jumper cables, ensure that they do not become entangled in the
cooling fans or belt.
■To prevent damaging the vehicle
The exclusive jump starting terminal is to be used when charging the 12-volt battery
from another vehicle in an emergency. It cannot be used to jump start another vehicle.

7028-2. Steps to take in an emergency
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■“Engine Coolant Temp High Stop in a Safe Place See Owner’s Manual” is
shown on the multi-information displayStop the vehicle in a safe place and turn off the air conditioning system, and
then stop the hybrid system.
If you see steam:
Carefully lift the hood after the steam subsides.
If you do not see steam:
Carefully lift the hood.
After the hybrid system has
cooled down sufficiently, inspect
the hoses and radiator core (radi-
ator) for any leaks.Radiator
Cooling fans
If a large amount of coolant leaks,
immediately contact your Lexus
dealer.
The coolant level is satisfactory if
it is between the “FULL” and
“LOW” lines on the reservoir.Reservoir
“FULL” line
“LOW” line
Radiator cap
If your vehicle overheats
The following may indicate that your vehicle is overheating.
●The needle of the engine coolant temperature gauge ( P. 96) enters the
red zone, or a loss of hybrid system power is experienced. (For example, the
vehicle speed does not increase.)
●“Engine Coolant Temp High Stop in a Safe Place See Owner’s Manual” or
“Hybrid System Overheated Reduced Output Power” is shown on the
multi-information display.
●Steam comes out from under the hood.
Correction procedures
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7038-2. Steps to take in an emergency
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When trouble arises
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Add coolant if necessary.
Water can be used in an emergency
if coolant is unavailable.
Start the hybrid system and turn the air conditioning system on to check
that the radiator cooling fans operate and to check for coolant leaks from
the radiator or hoses.
The fans operate when the air conditioning system is turned on immediately after a
cold start. Confirm that the fans are operating by checking the fan sound and air
flow. If it is difficult to check these, tu rn the air conditioning system on and off
repeatedly. (The fans may not operate in freezing temperatures.)
If the fans are not operating:
Stop the hybrid system immediately and contact your Lexus dealer.
If the fans are operating:
Have the vehicle inspected at the nearest Lexus dealer.
Check if “Engine Coolant Temp High Stop in a Safe Place See Owner’s
Manual” is shown on the multi-information display.
If the message does not disappear:
Stop the hybrid system and contact your Lexus dealer.
If the message is not displayed:
Have the vehicle inspected at the nearest Lexus dealer.
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