Lexus ES300 (2002 year). Manual - part 77

BODY ELECTRICAL – AIR CONDITIONING

BE-29

198BE32

Liquid Refrigerant

Gaseous Refrigerant

Multi-Flow Condenser

Condensing Portion

Modulator

Super-Cooling Portion

152BE40

High 
Pressure

Properly Recharged Amount

Point in which Bubbles Disappear

Amount of Refrigerant

5. Condenser

General

The ’02 ES300 has adopted sub-cool condenser in which a multi-flow condenser (consisting of two cooling
portions: a condensing portion and a super-cooling portion) and a gas-liquid separator (modulator) have
been integrated. This condenser has adopted the sub-cool cycle for its cooling cycle system to improve the
heat exchanging efficiency.

Sub-Cool Cycle

In the sub-cool cycle of the sub-cool condenser that has been adopted, after the refrigerant passes through
the condensing portion of the condenser. Both the liquid refrigerant and the gaseous refrigerant that could
not be liquefied are cooled again in the super-cooling portion. Thus, the refrigerant is sent the evaporator
in an almost completely liquefied state.

NOTE: The point at which the air bubbles disappear in the refrigerant of the sub-cool cycle is lower than

the proper amount of refrigerant with which the system must be filled. Therefore, if the system is
recharged with refrigerant based on the point at which the air bubbles disappear, the amount of re-
frigerant would be insufficient. As a result, the cooling performance of the system will be affected.
For the proper method of verifying the amount of the refrigerant and to recharge the system with
refrigerant, see the 2002 LEXUS ES300 Repair Manual (Pub. No. RM911U).

BODY ELECTRICAL – AIR CONDITIONING

BE-30

199BE65

211BE24

Solar Sensor

Sensor 
Portion

Filter 
Portion

211BE25

Exhaust Gas Smell

Clean Air Filter

Clean Air

Spreading Type 
Activated 
Charcoal

Deodorizing Layer

Service Tip

 Do not wash the clean air filter with water or use an air blower to clean it because the clean air filter

contains spreading type activated charcoal.

 The clean air filter on U.S.A. model should be changed at 7,500 miles. On Canada model, it should

be changed at 16,000km. However, it varies with the use conditions (or environment).

6. Solar Sensor

 Detects (in the from of changes in the current that flows through the built-in photo diode) the changes in

the amount of sunlight at the driver and front passenger sides (2 directions) and outputs them to the air
conditioning ECU.

 This sensor is integrated with the automatic light control sensor that is used in the automatic light control

system.

 This sensor is located in the driver side above the instrument panel.

7. Clean Air Filter

A deodorizing function that eliminates the exhaust gas smell that enters the cabin from the outside has been
added to the conventional clean air filter. This clean air filter uses spreading type activated charcoal in the
deodorizing layer to eliminate the exhaust gas (include acetaldehyde) smell.

BODY ELECTRICAL – AIR CONDITIONING

BE-31

7. Air Conditioning ECU

General

The air conditioning ECU has following control.

Control

Outline

’02

ES300

’01

ES300

Outlet Air
Temp.
Control

In response to the temperature control switch setting, the required outlet
air temperature, evaporator temperature sensor, and engine coolant
temperature sensor compensations are used by the air mix control
damper control to calculate a tentative damper opening angle, through
an arithmetic circuit in the air mix damper, to arrive at a target damper
opening angle.





Control

The temperature setting for the driver and front passenger is controlled
independently in order to provide a separate air temperature for the right
and left outside. Thus, air conditioning that accommodates the
occupants’ preferences has been realized.



—

Blower
Control

This function controls the operation of the blower motor in accordance
with the signals from the engine coolant temperature sensor, evaporator
temperature sensor, and the solar sensor. In addition, it protects the
blower motor controller from the sudden drive current that occurs when
the blower motor is activated.





Air Outlet
Control

When the AUTO switch has been turned ON, automatic control causes
the servomotor (for air mix control) to rotate to a desired position in
accordance with the target damper opening, which is based on the
calculation of the required outlet air temperature.
Furthermore, under automatic control, the potentiometer in the
servomotor (for air mix control) is used to detect the actual damper
opening, as opposed to the calculated target damper opening, so that
control can be effected to match the actual damper opening to the
calculated target damper opening.





In accordance with the engine coolant temperature, outside air
temperature, amount of sunlight, required blower outlet temperature,
and vehicle speed conditions, this control automatically switches the
blower outlet to the FOOT / DEF mode to prevent the window from
becoming fogged when the outside air temperature is low.



—

Drives the servomotor (for air inlet) according to the operation of the air
inlet control switch and fixes the dampers in the FRESH or RECIRC
position.





Air Inlet
Control

When selecting RECIRC mode with a manual operation, if the outside
air temperature is low and the refrigerant pressure has malfunction, the
air conditioning ECU automatically switched the air inlet mode to the
FRESH mode.
However, if the outside air temperature is much lower than the specified
temperature, in spite of the malfunction of the refrigerant pressure, the
air conditioning ECU automatically switches the air inlet mode to the
FRESH mode.



—

When selecting RECIRC mode with a manual operation, if the
compressor turns OFF, the air conditioning ECU automatically
switched the air inlet mode to the FRESH mode.



—

(Continued)

BODY ELECTRICAL – AIR CONDITIONING

BE-32

Control

Outline

’02

ES300

’01

ES300

Compressor
Control

This control turns OFF the magnetic clutch of the compressor when
the blower motor is turned OFF at the time the engine coolant
temperature is below a predetermined value, an abnormal
refrigerant pressure has been input, or the discharge temperature of
the evaporator is below a predetermined value.





Control

When the DEF mode switch is turned on, the magnetic clutch relay
is activated automatically to engage the compressor. Also, when the
blower is turned off, and the front defroster switch is turned on, the
blower will turn on in the automatic control condition.





Seat Heater
Control*

The HI, LO, and OFF settings of the seat heater can be switched by
pressing the seat heater switch (for driver or front passenger).
Based on the signals from the temperature sensor that is built into
the seat heater, the air conditioning ECU turns the built-in seat
heater relay ON/ OFF in order to regulate the temperature that suits
the set mode.
Turning OFF the ignition switch will turn off the set heater.



—

Rear Window
Defogger
Control

When switching the rear window defogger ON, the rear window
defogger and outside rear view mirror heaters will operate. Then,
after 15 minutes have passed, the switch will automatically turn
OFF.





Outer
Temperature
Indication
Control

Based on the signals from the ambient temperature sensor, this
control calculates the outside temperature, which is then corrected
in the air conditioning ECU, and shown in the air conditioning
control panel.





Self-
Diagnosis

Checks the sensor in accordance with operation of the air
conditioning switches, then heater control panel display portion a
DTC (Diagnosis Trouble Code) to indicate if there is a malfunction
or not (sensor check function).





Diagnosis

Drives the actuators through a predetermined sequence in
accordance with the operation of the air conditioning switches
(actuator check function).





*: With Seat Heater Model