Air Conditioning System (Diagnostics - Introduction): Overview Lexus IS III

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1. PRECAUTION FOR DISCONNECTING CABLE FROM NEGATIVE BATTERY TERMINAL NOTE: When disconnecting the cable from the negative (-) battery terminal, initialize the following system after the cable is reconnected. System Name See Procedure Air Conditioning System Refer to «INITIALIZATION [04/2013 - ]»(ref-665529-S01115916402014102400000) Variable Gear Ratio Steering System
2. DO NOT HANDLE REFRIGERANT IN AN ENCLOSED AREA OR NEAR AN OPEN FLAME *a Charging Cylinder
3. ALWAYS WEAR EYE PROTECTION
4. BE CAREFUL NOT TO GET LIQUID REFRIGERANT IN YOUR EYES OR ON YOUR SKIN If liquid refrigerant gets in your eyes or on your skin. Wash the area with lots of cold water. WARNING: Do not rub your eyes or skin. Apply clean petroleum jelly to the skin. Go immediately to a hospital or see a physician for professional treatment.
5. NEVER HEAT CONTAINER OR EXPOSE CONTAINER TO AN OPEN FLAME
6. BE CAREFUL NOT TO DROP CONTAINER OR APPLY PHYSICAL SHOCKS TO IT
7. DO NOT OPERATE COMPRESSOR WITHOUT ENOUGH REFRIGERANT IN REFRIGERANT SYSTEM If there is not enough refrigerant in the air conditioning system, oil lubrication will be insufficient and the compressor may be damaged. Necessary care should be taken to avoid this.
8. DO NOT OPEN HIGH PRESSURE MANIFOLD VALVE WHILE COMPRESSOR IS OPERATING *a Wrong *b Okay Open and close only the low pressure valve. If the high pressure valve is opened, refrigerant will flow in the reverse direction causing the charging cylinder to rupture.
9. BE CAREFUL NOT TO OVERCHARGE SYSTEM WITH REFRIGERANT If the system is overcharged with refrigerant, it causes problems such as insufficient cooling, poor fuel economy, engine overheating, etc.
10. DO NOT OPERATE ENGINE AND COMPRESSOR WITH NO REFRIGERANT WARNING: Doing so may damage the inside of the compressor because the compressor parts always move regardless of whether the air conditioning system is turned on or off.
11. SUPPLEMENTAL RESTRAINT SYSTEM (SRS) This vehicle is equipped with a Supplemental Restraint System (SRS) such as the driver, front passenger, side, and curtain shield airbags. Failure to carry out service operations in the correct sequence could cause the SRS to unexpectedly deploy during servicing, possibly leading to a serious accident. Before servicing (including removal or installation of parts, inspection or replacement), be sure to read the precautionary notices. Refer to «PRECAUTION [04/2013 - ]»(ref-665792-S23553771532014102400000)
12. GENERAL PRECAUTION While using the battery during inspection, do not bring the positive (+) and negative (-) tester probes too close to each other as a short circuit may occur.
13. CHECK MEMORY CALL FUNCTION Memory registration. NOTE: Be sure to have all the electrical key transmitter sub-assemblies prepared and available before performing registration. Lock the doors using an electrical key transmitter sub-assembly before performing registration. Sit in the driver seat while holding only the electrical key transmitter sub-assembly to be registered. Start the engine and turn on the air conditioning system. Turn the engine switch off. HINT: It is necessary to register each transmitter individually. Check memory call function. With the ID code of the transmitter registered in memory, check that the air conditioning operation is restored to its previous state when the engine is started. HINT: The recalled settings will differ depending on the registered transmitter.

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COMMUNICATION TABLE

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1. GENERAL The air conditioning system has the following controls. Control Outline Neural Network Control This control is capable of performing complex control by artificially simulating the information processing method of the nervous system of living organisms in order to establish a complex input/output relationship similar to that of a human brain. Outlet Air Temperature Control Based on the temperature set by the temperature control dial, neural network control calculates outlet air temperature based on input signals from various sensors. Dual Control The temperature settings for the driver and front passenger are controlled independently in order to provide separate vehicle interior temperatures for the right and left sides of the vehicle. Thus, air conditioning that accommodates the occupants' preferences has been realized. Blower Control Controls the blower motor in accordance with the airflow volume that has been calculated by neural network control based on input signals from various sensors. Air Outlet Control Automatically switches the air outlets in accordance with the outlet mode that has been calculated by neural network control. In accordance with the engine coolant temperature, ambient air temperature, amount of sunlight, required blower, outlet temperature and vehicle speed conditions, this control automatically switches the blower outlet to foot/defroster mode to prevent the windows from becoming fogged up when the ambient air temperature is low. Air Inlet Control Automatically controls the air inlet control damper to help achieve the calculated outlet air temperature that is required. Drives the air inlet control servo motor according to the operation of the air inlet control switch and moves the dampers to the fresh or recirculation position. Compressor Control Through the calculation of the target evaporator temperature based on various sensor signals, the air conditioning amplifier optimally controls discharge capacity by regulating the opening extent of the compressor solenoid valve. The air conditioning amplifier assembly compares the pulley speed signals (transmitted by the lock sensor located on the compressor) with the engine speed signal (which are transmitted by the ECM (crankshaft position sensor)). When the air conditioning amplifier assembly determines that the pulley is locked, it turns off the magnetic clutch. Micro Dust and Pollen Filter Mode Control Activated by the micro dust and pollen filter mode switch operation. Switches the air vent to face mode. Sends air which has passed through the clean air filter to the area around the upper part of the bodies of the driver and front passenger. This air is filtered by the clean air filter in order to remove pollen. Defroster Control Defroster control logic is used to improve defroster performance. PTC Heater Control*1 When the engine is running, and the blower motor with fan sub-assembly is turned on, the air conditioning amplifier assembly turns on the quick heater assembly if the conditions listed below are met. Engine coolant temperature is below specified temperature. Outside temperature is below specified temperature. Tentative air mix damper opening angle is above the specified value (MAX HOT). Rear Defogger Control Refer to Rear Defogger System. Refer to «SYSTEM DESCRIPTION [04/2013 - ]»(ref-665880-S07143497422014102400000) ECO Mode Control When the combination switch assembly (ECO mode switch) is turned on, the air conditioning amplifier assembly limits the air conditioning system performance. Diagnosis A Diagnostic Trouble Code (DTC) is stored in memory when the air conditioning amplifier assembly detects a problem with the air conditioning system. Memory Call Control Memorizes the air conditioning settings when the engine switch is turned from on (IG) to off in accordance with the ID code of the electrical key transmitter sub-assembly that is used to operate the vehicle. The memory call control then recalls the settings of the electrical key transmitter sub-assembly used when the engine switch is turned on (IG). This function operates when both of the following conditions are met. The driver door is unlocked using the unlock sensor, and then the driver door is opened. Engine switch is turned on (IG). *1: w/ PTC Heater
2. NEURAL NETWORK CONTROL In previous automatic air conditioning systems, the air conditioning amplifier assembly determined the required outlet air temperature and blower air volume in accordance with the calculation formula that has been obtained based on information received from the sensors. However, because the senses of a person are rather complex, a given temperature is sensed differently, depending on the environment in which the person is situated. For example, a given amount of solar radiation can feel comfortably warm in a cold climate, or extremely uncomfortable in a hot climate. Therefore, as a technique for effecting a higher level of control, a neural network has been adopted in the automatic air conditioning system. With this technique, the data that has been collected under varying environmental conditions is stored in the air conditioning amplifier assembly. The air conditioning amplifier assembly can then effect control to provide enhanced air conditioning comfort. The neural network control consists of neurons in the input layer, intermediate layer and output layer. The input layer neurons process the input data of the outside temperature, the amount of sunlight and the room temperature based on the outputs of the switches and sensors, and output them to the intermediate layer neurons. Based on this data, the intermediate layer neurons adjust the strength of the links among the neurons. The sum of these is then calculated by the output layer neurons in the form of the required outlet temperature, solar correction, target airflow volume and outlet mode control volume. Accordingly, the air conditioning amplifier assembly controls the servo motors and blower motor in accordance with the control volumes that have been calculated by the neural network control.
3. MODE POSITION AND DAMPER OPERATION Mode Position and Damper Operation. *1 Recirculated Air *2 Air Inlet Control Door *3 Fresh Air *4 Air Refiner Element *5 Blower Motor with Fan Sub-assembly *6 No. 1 Cooler Evaporator Sub-assembly *7 Quick Heater Assembly (w/ PTC Heater) *8 Side Register (Front Passenger Side) *9 Center Register (Front Passenger Side) *10 Mode Control Door (for Front Passenger Footwell Register) *11 Front Footwell Register Duct (Front Passenger Side) *12 Rear Footwell Register Duct *13 Console Box Register *14 Front Footwell Register Duct (Driver Side) *15 Mode Control Door (for Driver Footwell Register) *16 Center Register (Driver Side) *17 Side Register (Driver Side) *18 Side Defroster *19 Center Defroster *20 Heater Radiator Unit Sub-assembly *21 Inside-and-outside Dual Air Layer Control Door *22 Mode Control Door (for Defroster) *23 Air Mix Control Door *24 Mode Control Door (for Front Passenger Center and Side Register) *25 Mode Control Door (for Console Box Register and Rear Passenger Footwell Register Duct) *26 Mode Control Door (for Driver Center and Side Register) *27 Air Mix Control Door (for Driver Side Upper Layer) *28 Air Mix Control Door (for Driver Side Lower Layer) *29 Air Mix Control Door (for Front Passenger Side Lower Layer) *30 Air Mix Control Door (for Front Passenger Side Upper Layer) *a View from A *b To Center and Side Defrosters *c To Driver Side Center and Side Registers *d To Driver Side Footwell Register Duct *e To Front Passenger Side Footwell Register Duct *f To Front Passenger Side Center and Side Register Control Damper Operation Position Door Position Operation Air Inlet Control Damper FRESH A2, B1 Brings in fresh air. RECIRCULATION A1, B2 Recirculates internal air. Inside-and-outside Dual Air Layer Control Door - (Auto Control) C1 - C2 Separates or integrates the upper layer and lower layer in response to the control conditions to control the inside-and-outside dual air layers. Air Mix Control Door MAX COLD to MAX HOT Temperature Setting D1 - D2*1 E1 - E2*2 F1 - F2*3 G1 - G2*4 Varies the mixture ratio of warm air and cool air in order to continuously regulate the temperature between hot and cold. Mode Control Door FACE J1, K1, L1, M1, N3, H1, I3 Air blows out of the front center register, side register and console box register. BI-LEVEL J2, K2, L2, M2, N2, H2, I3 Air blows out of the front center register, side register, console box register and front and rear footwell register ducts. Air may blow out from the center defroster and side defroster depending on the cabin environment (I2). FOOT J3, K3, L3, M3, N2, H3, I3*5 or I2*6 Air blows out of the front footwell register and rear footwell register ducts. In addition, air blows out slightly from the front center register, side register and console box register. Air blows out slightly from the center defroster and side defroster when FOOT MODE is turned on by the automatic control. FOOT AND DEFROSTER J3, K3, L2, M2, N2, H2, I1 Defrosts the windshield through the center defroster and side defroster, while air is also blown out from the front footwell register and rear footwell register ducts. In addition, air blows out slightly from the front center register, side register and console box register. DEFROSTER J4, K4, L1, M1, H1, I1 Defrosts the windshield through the center defroster and side defroster ducts. HINT: *1: For driver side front register and side register *2: For front passenger side front register and side register *3: For driver side front footwell register *4: For front passenger side front footwell register *5: When FOOT MODE is selected by a manual operation. *6: When FOOT MODE is turned on by the automatic control or FOOT MODE is selected by a manual operation from except FOOT MODE.
4. AIR OUTLETS AND AIRFLOW VOLUME Air Outlets and Airflow Volume. Mode Selection FACE FOOT DEF Auto Manual Center Side Rear Front Rear F A B C D E FACE-U FACE-L FACE-R B/L FOOT-D FOOT-R FOOT-F FOOT/DEF DEF The size of each circle o indicates the ratio of airflow volume.
5. COMPRESSOR General: The compressor is a continuously variable capacity type in which its capacity can be varied in accordance with the cooling load of the air conditioning system. The compressor consists of a pulley, shaft, lug plate, swash plate, piston, shoe, crank chamber, cylinder, solenoid valve with built-in crank chamber to suction passage (CS) valve, oil separator and variable suction side throttle. The cooler compressor assembly has an A/C lock sensor that detects whether the compressor is locked. A solenoid valve is provided to enable the suction pressure to be controlled as desired. The crank chamber to suction passage (CS) valve, built into the solenoid valve, operates in accordance with the suction pressure. The oil separator is installed in the refrigerant passage to separate compressor oil from the refrigerant that is discharged. This helps to prevent the compressor oil from flowing into the air conditioning system and reducing cooling effectiveness. Solenoid Valve Operation: The crank chamber is connected to the suction passage. A solenoid valve is provided between the suction passage (low pressure) and the discharge passage (high pressure). The solenoid valve operates under duty cycle control in accordance with the signals from the air conditioning amplifier assembly. 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 also increases. 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. CS Valve Operation: The CS valve consists of passage A and passage B. If the vehicle is left parked for a long period, refrigerant may accumulate in the crank chamber due to the heat capacity difference. The solenoid control valve is controlled by the air conditioning amplifier assembly. While the compressor is operating, the solenoid control valve pushes down the CS valve rod and opens passage A. Under the above condition, only if the refrigerant accumulates in the crank chamber, the crank chamber pressure will become high. As a result, the bellows will contract because of the pressure difference with its internal pressure (vacuum), and opens passage B. This causes the accumulated refrigerant to be drawn in via passage A and passage B, clearing the accumulated refrigerant earlier and ensuring a more immediate cooling effect.
6. A/C LOCK SENSOR The A/C lock sensor sends A/C pulley speed signals to the air conditioning amplifier assembly. The air conditioning amplifier assembly determines whether the A/C compressor is locked or not by using those signals and engine speed signals.
7. NO. 1 COOLER THERMISTOR The No. 1 cooler thermistor detects the temperature of the cool air immediately after the evaporator in the form of resistance changes, and outputs it to the air conditioning amplifier assembly.
8. BLOWER MOTOR WITH FAN SUB-ASSEMBLY The blower motor has a built-in blower controller, and is controlled using duty control performed by the air conditioning amplifier assembly.
9. MICRO DUST AND POLLEN FILTER MODE CONTROL When the micro dust and pollen filter mode switch is pressed, micro dust and pollen filter mode control is activated. Then, the air vent is switched to face mode and recirculated pollen-free air flows in the area around the upper part of the bodies of the driver and front passenger. When the micro dust and pollen filter mode switch signal is input to the air conditioning amplifier assembly, the air conditioning amplifier assembly controls the cooler compressor assembly, air inlet control servo motor, air outlet control 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 (41°F) maximum), it will operate for approximately 1 minute. After this control stops operating, the air conditioning amplifier assembly controls the air conditioning system using AUTO mode.
10. BUS CONNECTOR (AIR CONDITIONING HARNESS ASSEMBLY) Bus connectors are used in the wire harness that connects the servo motors to the air conditioning amplifier assembly. *a Example *b Bus Connector (to No. 5 Air Conditioning Radiator Damper Servo Sub-assembly (Driver Side Lower Air Mix)) *c Bus Connector (to No. 2 Air Conditioning Radiator Damper Servo Sub-assembly (Driver Side Upper Air Mix)) *d Bus Connector (to No. 3 Air Conditioning Radiator Damper Servo Sub-assembly) *e Bus Connector (to No. 1 Air Conditioning Radiator Damper Servo Sub-assembly) *f Bus Connector (to No. 2 Air Conditioning Radiator Damper Servo Sub-assembly (Front Passenger Side Upper Air Mix)) *g Bus Connector (to No. 4 Air Conditioning Radiator Damper Servo Sub-assembly (Front Passenger Side Lower Air Mix)) *h Bus Connector (to No. 1 Blower Damper Servo Sub-assembly) *i to Air Conditioning Amplifier Assembly *j to No. 1 Cooler Thermistor Each bus connector has a built-in communication/driver IC which communicates with the air conditioning amplifier assembly, actuates the servo motor, and has a position detection function. This enables bus communication for the servo motor wire harness, for a more lightweight construction and a reduced number of wires.
11. SERVO MOTOR A pulse pattern type servo motor consists of a printed circuit board and a servo motor. The printed circuit board has three contact points, and can transmit two ON-OFF signals to the air conditioning amplifier assembly based on the difference of the pulse phases. The bus connector can detect the damper position and movement direction with these signals.
12. QUICK HEATER ASSEMBLY General The quick heater assembly is located above the heater core in the air conditioning radiator assembly. The quick heater assembly consists of a PTC element, aluminum fins, and brass plates. When current is applied to the PTC element, it generates heat to warm the air that passes through the unit. *1 Quick Heater Assembly *2 Brass Plate *3 PTC Element *4 Aluminum Fin Quick Heater Assembly Operating Conditions The quick heater assembly is turned on and off by the air conditioning amplifier assembly in accordance with the engine coolant temperature, ambient temperature, temperature setting, and electrical load (generator power ratio).
13. ECO MODE CONTROL Under the control of ECO mode, the air conditioning amplifier assembly restricts the air conditioning system performance under specified conditions, thus improving fuel economy.
14. COOLER (ROOM TEMP. SENSOR) THERMISTOR The cooler (room temp. sensor) thermistor detects the cabin temperature based on changes in the resistance of its built-in thermistor and sends a signal to the air conditioning amplifier assembly.
15. THERMISTOR ASSEMBLY The thermistor assembly detects the outside temperature based on changes in the resistance of its built-in thermistor and sends a signal to the air conditioning amplifier assembly.
16. AUTOMATIC LIGHT CONTROL SENSOR The automatic light control sensor detects (in the form of changes in the current that flows through the built-in photo diode) the changes in the amount of sunlight and outputs these sunlight strength signals to the air conditioning amplifier assembly.
17. AIR CONDITIONER PRESSURE SENSOR The air conditioner pressure sensor detects the refrigerant pressure and outputs it to the air conditioning amplifier assembly in the form of voltage changes.

See also:
• DIAGNOSTIC TROUBLE CODE TABLE [04/2013 - ]