AIR CONDITIONING SYSTEM

Automatic Recirculation Control

1. When the automatic recirculation control is operating, the air conditioning amplifier assembly automatically changes the air inlet mode to the fresh air or recirculate air mode based on signals from the smog ventilation sensor, cooler (ambient temp. sensor) thermistor and cooler (room temp. sensors) thermistor when the AUTO air inlet mode is selected.

   
   

   • The air conditioning amplifier assembly detects harmful elements (CO, HC and NOx) based on smog ventilation sensor signals and automatically switches the air inlet mode to the recirculate air mode to prevent such harmful elements from entering the cabin.

   • The air conditioning amplifier assembly detects room temperature based on a cooler (room temp. sensor) thermistor signal and automatically switches the air inlet mode to the recirculate air mode to prevent the room temperature from becoming too high.

   • The air conditioning amplifier assembly detects the outside temperature based on the cooler (ambient temp. sensor) thermistor signal and automatically switches the air inlet mode to the fresh air mode to prevent the windshield from fogging up.

   

   Note

   The smog ventilation sensor cannot detect elements such as the smoke from a bonfire or factory exhaust, foul or animal odors, and dirt or dust particles.

   Therefore, the air inlet modes are not changed in accordance with those elements.

Micro Dust and Pollen Filter Mode Control

1. When the micro dust and pollen filter switch is pressed, the micro dust and pollen filter control is activated. Then, the air vent is switched to the FACE mode and recirculated pollen-free airflows in the area around the upper part of the bodies of the driver and front passenger.

   
   

   • When the micro dust and pollen filter switch signal is input to the air conditioning amplifier assembly, the air conditioning amplifier assembly controls the compressor with pulley assembly, air inlet servo motor, air vent servo motor and blower motor as shown in the timing chart below.

   • This control usually operates for approximately 3 minutes. However, when the outside temperature is low (5°C maximum), the control will operate for approximately 1 minute.

   • After this control stops operating, the air conditioning amplifier assembly controls the air conditioning system using the AUTO mode.

   

Clean Air Filter Clogging Judgment

1. The airflow volume decreases when the filter becomes clogged, causing insufficient cooling or heating performance of the system. When the filter is clogged, the warning message is displayed on the multi-information display of the combination meter assembly to alert the driver to replace the clean air filter.

2. The air conditioning amplifier assembly transmits the signals to the meter ECU so as to display the message "Change the Air Conditioning Filter" on the multi-information display of the combination meter assembly once the air conditioning amplifier assembly calculates the airflow volume of the air outlet in accordance with the inlet mode and blower level and detects the blockage of the clean air filter.

   

Air Quality Control

1. This control, which is linked to the automatic recirculation control, operates the rear air conditioning and air purifier blower motor to improve the efficiency of the air purifier in order to supply the vehicle cabin with good quality air.

   

Rear Air Conditioning Control Panel (Rear Power Seat Switch)

1. On models with rear air conditioning system, the set temperatures of both the seats and the operation mode of the rear air conditioning can be changed with the rear power seat switch.

2. On the Liquid Crystal Display (LCD) of the rear power seat switch, the set temperature status of the rear air conditioning status and both are displayed.

   

   Text in Illustration

   *a

   Rear Air Conditioning Switch and Display Section

   -

   -

Front Air Conditioning Unit

1. A semi-center location air conditioning unit, in which the No. 1 cooler evaporator subassembly and heater radiator unit sub-assembly are placed in the vehicle's longitudinal direction, is used. As a result, the air conditioning unit has been made compact and lightweight.

   

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   *1	No. 1 Cooler Evaporator Sub-assembly	*2	Heater Radiator Unit Sub-assembly
   	Front	-	-

Heater Radiator Unit Sub-assembly

1. A compact, lightweight and highly efficient Straight Flow Aluminum (SFA)-II type heater radiator unit sub-assembly is used for the air conditioning system.

   

No. 1 Cooler Evaporator Sub-assembly

1. A Revolutionary super-slim Structure (RS) type evaporator is used. Placing the tanks at the top and the bottom of the evaporator and using a micropore tube construction provide the following benefits:

   
   

   • Improved heat exchange efficiency

   • More uniform temperature distribution

   • A thinner evaporator

2. The evaporator body has been coated with a type of resin that contains an antibacterial agent in order to minimize the source of foul odor and the propagation of bacteria. The substrate below this coating consists of a chromate-free layer to help protect the environment.

   

   Text in Illustration

   *1	Tank	*2	Micropore Tube
   *3	Cooling Fin	-	-

Air Mix Control Film Damper

1. The non-sliding film damper is provided on the air mix control damper. This film damper is independently disposed inside the front air conditioning unit, and thus respective temperature control can be performed. Moreover, the film-like damper is independently fitted on both the warm and cool air sides, thus, the airflow can be independently adjusted on both sides.

2. The airflow volume can be adjusted by increasing the opening of the film. When the opening of the film is made large, the airflow volume is increased, and when the opening of the film is made small, the airflow volume is decreased.

3. In the non-sliding film damper, the spiral shaft fitted in the cassette case of the air mix servo motor is rotated and the winding shaft is moved along the spiral shaft while being vertically rotated, and thus the film damper can be opened and closed and quietness can be enhanced.

   

   Text in Illustration

   *1	Film Pressing Member	*2	Winding Shaft
   *3	Servo motor	*4	Helical Shaft Cover
   *5	Helical Shaft Brace	*6	Helical Shaft
   *7	Gear	*8	Cassette Case
   *9	Front Air Conditioning Unit	-	-
   *a	Cool Air Side	*b	Warm Air Side
   *c	Image of Airflow Adjustment	*d	Airflow
   *e	Airflow Volume Down	*f	Airflow Volume UP

Bus Connector

1. A bus connector is used in the wire harness connection that connects the servomotor from the air conditioning amplifier assembly.

   

   Text in Illustration

   *1	Bus Connector	*2	Air Conditioning Harness Assembly
   *a	To Air Conditioning Amplifier Assembly	-	-

2. The bus connector has a built-in communication/driver IC which communicates with each servomotor connector, actuates the servomotor, and has a position detection function. This enables bus communication for the servomotor wire harness for a more lightweight construction and a reduced number of wires.

   

   Text in Illustration

   *A	Models with Bus Connector	*B	Models without Bus Connector
   *1	Air Conditioning Amplifier Assembly	*2	Bus Connector
   *3	Communication Driver IC	*4	Servomotor
   *5	Communication IC	*6	CPU
   *7	Driver IC	-	-

Servo Motor

1. The pulse pattern type servo motor consists of a printed circuit board and a servomotor. The printed circuit board has 3 contact points, and transmits 2 on-off signals to the air conditioning amplifier assembly for the difference of the pulse phase. The smart connector detects the damper position and movement direction with this signal.

   

PTC Heater (Quick Heater Assembly) (Models with Quick Heater Assembly)

1. The PTC heater is located above the heater core in the air conditioning unit.

2. The PTC heater consists of a PTC element and an aluminum fin. When current is applied to the PTC element, it generates that to warm the air that passes through the unit.

   

   Text in Illustration

   *1	PTC Heater (Quick Heater Assembly)	*2	PTC Element
   *3	Aluminum Fin	-	-

Clean Air Filter (Air Refiner Element)

1. An air refiner element is used, which can remove odors from the cabin and exhaust gases. Activated charcoal is used for odor reduction, and the life of the air refiner has been prolonged by reducing the amount of desorbing odor which has been already absorbed once.

2. In addition, the fixing material used to adhere activated charcoal to the air refiner element has been optimized and pressure loss reduction has been aimed for in the activated charcoal layer, thus enabling a finer non-woven fabric to achieve removal of micro particles such as pollen.

   

   Text in Illustration

   *1	Air Refiner Element	*2	Non-woven Fabric (Upper Flow Side)
   *3	Non-woven Fabric (Lower Flow Side)	*4	Fixing Material (in Sheet Form)
   *5	Fixing Material (in Particle Form)	*6	Activated Charcoal
   *a	Filter Cross Section	*b	Airflow

[nanoe] Generator (No. 1 Ion Generator Sub-assembly)

1. The [nanoe] generator (No. 1 ion generator sub-assembly) is provided to enhance the air quality and comfort in the cabin.

2. The [nanoe] outlet of the [nanoe] generator is attached under the heater to register duct. This allows [nanoe] to be released together with air from the driver side center register.

3. The [nanoe] generator is controlled by the air conditioning amplifier assembly and operates when the [nanoe] generator switch is pressed and the blower is on.

   

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   *1

   Center Resistor (Driver Side)

   *2

   [nanoe] Generator (No. 1 Ion Generator Sub-assembly)

   Note

   
   

   • The [nanoe] generator uses a high voltage, which is hazardous. Therefore, if the [nanoe] generator requires repairs, be sure to have them carried out at a Lexus dealer.

   • Do not apply any type of spray (such as a cleaning solvent or hair spray) or stick any foreign matter into the [nanoe] ion outlet, as this could cause improper operation or a malfunction.

   • It is normal for the [nanoe] generator to emit a slight sound during operation. This sound is created when electrons collide with the electrode while [nanoe] are being generated.

Rear Cooling Unit

1. The rear cooling unit assembly is mounted under the package tray trim.

2. The cool box fitted in the innermost part of the armrest can be cooled down by utilizing cool air from the rear cooling unit assembly.

3. Both the front and rear evaporators use the same revolutionary super-slim structure.

4. The blower motor has an built-in blower controller and is controlled with the duty control from the air conditioning amplifier assembly.

5. As in the front air conditioning unit, the servo motor fitted to the rear air conditioning unit is connected to the air conditioning amplifier assembly with the bus connector due to the lightweight construction and a reduced number of wires. Furthermore, the pulse pattern type servo motor is used for the both the front and rear air conditioning unit assemblies.

   

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   *1	Rear Air Outlet Servomotor (for RH Side)	*2	Rear Exhaust Mode Servomotor
   *3	Rear Air Mode Damper Servomotor	*4	Rear Evaporator Sub-assembly
   *5	Rear Air Outlet Servomotor (for LH Side)	-	-

Rear Air Pulifier (Rear Cooler Filter)

1. This filter is constituted of 2 layers of the electret layer and active charcoal layer. Dust in the cabin can effectively be collected in the electret layer made of high macromolecular fabric to which static electricity is applied.

   

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   *1	Filter Cover	*2	Rear Cooler Filter
   *3	Active Charcoal	*4	Electret Layer
   *a	Recirculated Air	*b	Clean Air

Cooler Condenser Assembly

1. A Multi-Flow (MF) type condenser is used. The condenser consists of 2 cooling portions: a condensing portion and a super-cooling portion, which are integrated together with a gas-liquid separator (modulator). This condenser uses a sub-cool cycle that offers excellent heat-exchange performance.

2. In the sub-cool cycle, 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 to the evaporator in an almost completely liquefied state.

   

   Text in Illustration

   *1	Condensing Portion	*2	Modulator
   *3	Super-cooling Portion	-	-
   *a	Gaseous Refrigerant	*b	Liquid Refrigerant

   Tech Tips

   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 was recharged with refrigerant based on the point at which the air bubbles disappear, the amount of refrigerant would be insufficient. As a result, the cooling performance of the system will be affected. If the system is overcharged with refrigerant, this will also lead to reduced performance.

   For the proper method of verifying the amount of refrigerant and for instructions on how to recharge the system with refrigerant, refer to the Repair Manual.

   

   *1	Proper Recharged Amount
   *2	High Pressure
   *3	Point in which Bubbles Disappear
   *4	Amount of Refrigerant

Compressor with Pulley Assembly

1. The compressor with pulley assembly is a continuously variable capacity type in which its capacity can be varied in accordance with the cooling load of the air conditioning.

2. This compressor with pulley assembly consists of the Damper Limiter (DL) type A/C pulley, shaft, lug plate, swash plate, piston, shoe, crank chamber, cylinder, and solenoid valve.

3. A solenoid valve that adjusts the suction pressure so that the compressor with pulley assembly capacity can be controlled as desired is provided.

4. The internal valve is provided to improve the compressor with pulley assembly durability under the high speed and large thermal load conditions. The internal valve is integrated into the solenoid valve.

   

   Text in Illustration

   *1	Shoe	*2	Crank Chamber
   *3	Lug Plate	*4	DL Pulley
   *5	Shaft	*6	Cylinder
   *7	Solenoid Valve	*8	Piston
   *9	Swash Plate	-	-

5. The crank chamber is connected to the suction passage. A solenoid valve is provided between the suction passage (LO pressure) and the discharge passage (HI pressure).

6. The solenoid valve operates under duty cycle control in accordance with the signals from air conditioning amplifier assembly.

   

7. When the solenoid valve closes (solenoid coil is energized), a difference in pressure is created and the pressure in the crank chamber decreases. Then, the pressure that is applied to the right side of the piston becomes greater than the pressure that is applied to the left side of the piston. This compresses the spring and tilts the swash plate. As a result, the piston stroke increases and the discharge capacity increases.

   

8. When the solenoid valve opens (solenoid coil is not energized), the difference in pressure disappears. Then, the pressure that is applied to the left side of the piston becomes the same as the pressure that is applied to the right side of the piston. Thus, the spring elongates and eliminates the tilt of the swash plate. As a result, there is no piston stroke and the discharge capacity is reduced.

   

9. The internal valve operates when compressor with pulley assembly speed has increased rapidly, the compressor with pulley assembly speed is high, or when thermal load has suddenly changed. As a result, the compressor with pulley assembly capacity is reduced, increasing the durability of the compressor with pulley assembly.

   

   *1	Air Conditioning Amplifier Assembly
   *2	Crank Chamber Pressure
   *3	Discharge Pressure
   *4	Internal Valve

DL Type Pulley

1. This pulley contains a damper to absorb the torque fluctuations of the engine and a limiter mechanism to protect the drive belt in case the compressor locks. In the event that the compressor locks, the limiter mechanism causes the spoke portion of the pulley to break, thus separating the pulley from the compressor with pulley assembly.

   

   Text in Illustration

   *1

   Spoke Portion

   *2

   Damper

Front Air Conditioning Mode Position and Damper Operation

Mode Position and Damper Operation

Control Damper	Operation Position		Damper Position	Operation
Air Inlet Control Damper	FRESH		A	Brings in fresh air.
	RECIRC		B	Recirculates internal air.
Air Mix Control Film Damper	MAX COLD to MAX HOT Temperature Setting		J, K	Varies the ratio of the fresh air and the recirculated air in order to regulate the temperature continuously from HOT to COLD.
Cool Air Bypass Damper	MAX COLD to MAX HOT Temperature Setting		H, I	Cool air blows outgo the front center register and side registers in order to adjust the temperature around the heads of the occupants during cooling or warming.
Mode Control Door		DEF	C	Defrosts the windshield through the center defroster, side defroster and side register.
		FOOT/DEF	D	Defrosts the windshield through the center defroster, side defroster, side register and rear center register, while air is also blown out from the front and rear footwell register ducts.
		FOOT	E	Blows air out of the footwell register duct, and side register. In addition, air blows out slightly from the center defroster and side defroster.
		BI-LEVEL	F	Blows air out of the front and rear center registers, side register, center pillar register and front and rear footwell register ducts.
		FACE	G	Blows air out of the front and rear center registers, center pillar register and side register.

Rear Air Conditioning Mode Position and Damper Operation

Air Outlets and Airflow Volume (Front Air Conditioning)

Air Outlets and Airflow Volume (Rear Air Conditioning)

Air Outlet Mode	Selectable Mode		Register
	Automatic	Manual	Roof (A)	Roof Side (B)
FACE