2012 Lexus HS250h cooling

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1-1. Hybrid system
HS250h_U_75050U
■Charging the hybrid battery (traction battery)
As the gasoline engine charges the hybrid battery (traction battery), the battery
does not need to be charged from an outside source. However, if the vehicle is left
parked for a long time the hybrid battery will slowly discharge. For this reason, be
sure to drive the vehicle at least once every few months for at least 30 minutes or
10 miles (16 km). If the hybrid battery becomes fully discharged and you are unable
to jump-start the vehicle with the 12-volt battery, contact your Lexus dealer.
■Charging the 12-volt battery
→P. 5 4 9
■After the 12-volt battery has discharg ed or has been changed or removed
The gasoline engine may not stop even if the vehicle is running on the hybrid battery
(traction battery). If this continues for a few days, contact your Lexus dealer.
■Sounds and vibrations specific to a hybrid vehicle
There may be no engine sounds or vibration even though the vehicle is able to
move. For safety, apply the parking brake and make sure to shift the shift position to
P when parked.
The following sounds or vibrations may occur when the hybrid system 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) behind the rear
seats when the hybrid system starts or stops.
●Sounds from the hybrid system may be heard when the trunk lid is open.
●Sounds may be heard from the transaxle when the engine is started or stopped,
or while the engine is idling.
●Engine sounds may be heard when accelerating sharply.
●Sounds may be heard due to regenerative braking when the brake pedal is
depressed and accelerator is loosened.
●Other sounds, such as motors and mechanical noises, may be heard from the
brake system when the brake pedal is depressed.
●Vibration may be felt when the gasoline engine starts or stops.
●Cooling fan sounds may be heard from the air intake vent on the side of rear left
seatback.
When driving in Eco drive mode, the fan noise may be louder than when driving
normally.

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1-1. Hybrid system
1
Before driving
HS250h_U_75050U
Hybrid battery air ventThere is an air intake vent on the
side of the rear left seatback for
the purpose of cooling the hybrid
battery (traction battery). If the
vent become blocked, the hybrid
battery may overheat, leading to a
reduction in hybrid battery output.
Emergency shut off system When a certain level of impact is detected by the impact sensor, the
emergency shut off system blocks off the high voltage current and stops
the fuel pump to minimize the risk of electrocution and fuel leakage. If the
emergency shut off system activates, your vehicle will not restart. To
restart the hybrid system, contact your Lexus dealer.
Hybrid warning messageA message is automatically displayed 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.
(→P. 5 1 2 )

40
1-1. Hybrid system
HS250h_U_75050U
Hybrid vehicle driving tips
For economical and ecological driving, pay attention to the following
points:
■Using Eco drive mode
When using Eco drive mode, the torque corresponding to the accelerator
pedal depression amount can be generated more smoothly than it is in
normal conditions. In addition, the operation of the air conditioning system
(heating/cooling) will be minimized, improving the fuel economy.
(→ P. 1 6 2 )
■Use of Hybrid System Indicator
Eco-friendly driving is possible by keeping the indicate of Hybrid System
Indicator within Eco area. ( →P. 171)
■When braking the vehicle
Make sure to operate the brakes gently and in good time. A greater
amount of electrical energy can be retained when slowing down.
■Delays
Repeated acceleration and deceleration, as well as long waits at traffic
lights, will lead to bad fuel consumption. Check traffic reports before leav-
ing and avoid delays as much as po ssible. When encountering a delay,
gently release the brake pedal to allow the vehicle to move forward slightly
while avoiding overuse of the accelera tor pedal. Doing so can help control
excessive gasoline consumption.
■ Highway driving
Control your speed and keep at a constant speed. Also, before stopping at
a toll booth or similar, allow plenty of time to release the accelerator and
gently apply the brakes. A greater amount of electrical energy can be
retained when slowing down.

162
2-1. Driving procedures
HS250h_U_75050U
■Selecting a driving mode
The following modes can be sele cted to suit driving conditions:
Eco drive mode
Suitable for improving the fuel
economy, because the torque
corresponding to the accelera-
tor pedal depression amount
can be generated more
smoothly than it is in normal
conditions and the operation of
the air conditioning system
(heating/cooling) will be mini-
mized.
When the “ECO MODE”
switch is pressed, the “ECO
MODE” indicator comes on in
the meter.
Po w e r m o d e
Suitable when the vehicle needs
to drive powerfully or travels in
mountainous areas.
When the “PWR MODE”
switch is pressed, the “PWR
MODE” indicator comes on in
the meter.

164
2-1. Driving procedures
HS250h_U_75050U
■About engine braking
When shift position B is selected, releasing the accelerator pedal will apply engine
braking.
• When the vehicle is driven at high speeds, compared to ordinary gasoline-fueled vehicles, the engine braking deceleration is felt less than that of other
vehicles.
• The vehicle can be accelerated even when shift position B is selected.
If the vehicle is driven continuously in the B position, fuel efficiency will become low.
Usually, select the D position.
■Using air conditioning in Eco drive mode
The Eco drive mode controls heating/cooling and fan speed operation to improve
fuel consumption. When you want to improve the effectiveness of the air condition-
ing system, adjust the fan speed or cancel the Eco drive mode.
For more information, refer to the “Navigation System Owner’s Manual”.
■Power mode automatic deactivation
Power mode is automatically deactivated if the “POWER” switch is turned off after
driving in power mode.
■Customization
Settings (e.g. Reverse warning buzzer) can be changed.
(Customizable features →P. 5 8 4 )
CAUTION
■When driving on slippery road surfaces
Do not accelerate or change the shift position suddenly.
Sudden changes in engine braking may cause the vehicle to spin or skid, resulting in
an accident.
■For the shift lever
Do not hang anything on the shift lever.
Doing so could prevent the shift lever fr om returning to position, causing unex-
pected accidents to occur when the vehicle is in motion.

266
HS250h_U_75050U
3-1. Using the air conditioning system and defogger
Automatic air conditioning system
Air outlets and fan speed are automatically adjusted according to the tem-
perature setting.
Vehicles with a navigation system
Owners of models equipped with a navigation system should refer to
the “Navigation System Owner’s Manual”.
Vehicles without a navigation system
Automatic
mode button
Driver’s side
temperature display
Dual
mode
button
Fan speed control buttons Air outlet display
Fan speed display
Passenger’s side
temperature display
Driver’s side
temperature
control buttons Outside/recirculated air
mode buttonWindshield
defogger button Passenger’s side
temperature
control buttons
Micro dust
and pollen
filter mode
button
“OFF” button Air outlet selector button
Cooling and
dehumidification
function on/off
button

433
4-3. Do-it-yourself maintenance
4
Maintenance and care
HS250h_U_75050U
CAUTION
The engine compartment contains many mechanisms and fluids that may move sud-
denly, 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 indicator on the “POWER” switch and the “READY” indicator
are both off.
●Keep hands, clothing and tools away from the moving fans and engine drive belt.
●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 rags, in the engine
compartment.
●Do not smoke, cause sparks or expose an open flame to fuel. Fuel fumes are flam-
mable.
■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. 444)
■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. Also, a backfire could cause a fire in the engine compartment.

437
4-3. Do-it-yourself maintenance
4
Maintenance and care
HS250h_U_75050U
Engine compartment
Engine coolant reservoir (→P. 4 4 2 )
Engine oil filler cap (→P. 4 3 9 )
Engine oil level dipstick (→P. 4 3 9 )
Power control unit coolant
reservoir ( →P. 4 4 2 )
Brake fluid reservoir (→P. 445)Fuse box ( →P. 4 6 9 )
Engine coolant radiator (→P. 444)
Power control unit coolant
radiator (→ P. 444)
Condenser ( →P. 444)
Electric cooling fans
Washer fluid tank (→P. 4 4 6 )