Air Conditioning System (Diagnostics - Introduction): Overview Lexus ES XV60

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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 systems after the cable is reconnected. System Name See Procedure Parking Assist Monitor System Refer to «INITIALIZATION [06/2012 - ]»(ref-598449-S08309221792014021400000) Power Trunk Lid System
2. DO NOT HANDLE REFRIGERANT IN AN ENCLOSED AREA OR NEAR AN OPEN FLAME TEXT IN ILLUSTRATION *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 THE 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 A/C 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 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. TEXT IN ILLUSTRATION *a Wrong *b Okay
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 A/C 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 [06/2012 - ]»(ref-598650-S23841933652014021400000) .
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.

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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. Automatic Recirculation Control Automatically changes the air inlet mode to FRESH or RECIRCULATION mode according to the level of harmful elements (CO, HC and NOx) in the outside air, cabin temperature, and outside temperature. Outlet Air Temperature Control Based on the temperature set by the temperature control switch, 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 the 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 and 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 assembly 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 When the engine switch is on (IG) and the rear defogger switch is pushed, the system is activated to keep the defogger heater on for approximately 15 minutes. However, the operating time of the rear defogger can be extended up to approximately 45 minutes when both of the following requirements are met: Ambient temperature: -3°C (27°F) or less Vehicle speed: 45 km/h (28 mph) or more ECO Mode Control When the ECO mode switch (integration control and panel assembly) 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. *1: w/ Quick Heater Assembly
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 outputs it 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 FUNCTIONS OF MAIN DAMPERS Control Damper Operation Position Damper Position Operation Air Inlet Control Damper FRESH A Allows fresh air to enter. RECIRCULATION B Causes internal air to recirculate. Air Mix Control Damper MAX COLD to MAX HOT Temperature Setting C - D - E (C' - D' - E') T - U - V Varies the mixture ratio of the warm air and cool air in order to regulate the temperature continuously between hot and cold. Air Outlet Control Damper DEF F, J, L, P, S, Y Defrosts the windshield through the center defroster, side defrosters and side registers. FOOT / DEF G, J, L, P, Q, X Defrosts the windshield through the center defroster, side defrosters, side registers, and rear center register, while air is also blown out from the front and rear footwell register ducts. FOOT H, J, L, P, Q, X Air blows out of the front and rear footwell register ducts, and side registers. In addition, air blows out slightly from the center defroster and side defrosters. BI-LEVEL I, K, N, O, R, X Air blows out of the front and rear center registers, side registers and front and rear footwell register ducts. FACE I, K, M, O, S, W Air blows out of the front and rear center registers, and side registers.
4. AIR OUTLETS AND AIRFLOW VOLUME Air Outlets and Airflow Volume MODE Selection Register Footwell Defroster Automatic Manual CTR SIDE RR FR RR CTR SIDE A B C D E F G FACE-U*1 B/L-U*2 FOOT-F*3 FOOT-R*4 FOOT-D*5 F/D DEF *1: Air blows out of registers only *2: Regular bi-level mode *3: Regular foot mode *4: Foot mode with large airflow volume from the rear footwell register ducts *5: Foot mode with large airflow volume from the defrosters 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, A/C flow sensor, 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 FLOW SENSOR The A/C flow sensor, which is mounted on the compressor, is used to detect the amount of refrigerant flow. The A/C flow sensor converts the amount of refrigerant flow that is detected to a voltage value to send to the air conditioning amplifier assembly. The voltage value sent from the A/C flow sensor changes depending on the amount of refrigerant flow. As the amount of refrigerant flow becomes larger, the voltage becomes lower. As the amount of refrigerant flow becomes smaller, the voltage becomes higher. The air conditioning amplifier assembly supplies 5 V to the A/C flow sensor and monitors changes in the voltage value sent from the A/C flow sensor. The air conditioning amplifier assembly then sends a signal to the ECM via CAN communication to allow the ECM to control the engine speed while the air conditioning is on.
7. 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.
8. AUTOMATIC RECIRCULATION CONTROL When automatic recirculation control is operating, the air conditioning amplifier assembly automatically changes the air inlet mode to FRESH or RECIRCULATION mode based on signals from the smog ventilation sensor, ambient temperature sensor (thermistor assembly) and room temperature sensor (cooler thermistor) when AUTO air inlet mode is selected. The air conditioning amplifier assembly detects harmful elements (CO, HC and NOx) based on a smog ventilation sensor signal and automatically switches the air inlet mode to RECIRCULATION mode to prevent such harmful elements (CO, HC and NOx) from entering the cabin. The air conditioning amplifier assembly detects cabin temperature based on a room temperature sensor signal and automatically switches the air inlet mode to RECIRCULATION mode to prevent the cabin temperature from becoming too high. The air conditioning amplifier assembly detects the outside temperature based on an ambient temperature sensor signal and automatically switches the air inlet mode to FRESH 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 mode is not switched automatically in accordance with those elements.
9. EVAPORATOR TEMPERATURE SENSOR (NO. 1 COOLER THERMISTOR) The evaporator temperature sensor (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.
10. 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.
11. 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 compressor with motor 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.
12. 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. 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.
13. SERVO MOTOR The 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.
14. PTC HEATER ASSEMBLY (QUICK HEATER ASSEMBLY) General The PTC heater assembly (quick heater assembly) is located above the heater core in the air conditioning radiator assembly. The PTC heater assembly (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. TEXT IN ILLUSTRATION *1 PTC Heater Assembly (Quick Heater Assembly) *2 Brass Plate *3 PTC Element *4 Aluminum Fin PTC Heater Assembly (Quick Heater Assembly) Operating Conditions The PTC heater assembly (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).
15. 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.
16. ROOM TEMPERATURE SENSOR (COOLER THERMISTOR) The room temperature sensor (cooler 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.
17. AMBIENT TEMPERATURE SENSOR (THERMISTOR ASSEMBLY) The ambient temperature sensor (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.
18. SOLAR SENSOR (AUTOMATIC LIGHT CONTROL SENSOR) The solar sensor (automatic light control sensor) consists of a photo diode, two amplifier circuits for the solar sensor (automatic light control sensor), and a frequency converter circuit for the light control sensor. The solar sensor (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 from the LH and RH sides (2 directions) and outputs these sunlight strength signals to the air conditioning amplifier assembly.
19. AIR CONDITIONING PRESSURE SENSOR The air conditioning pressure sensor detects the refrigerant pressure and outputs it to the air conditioning amplifier assembly in the form of voltage changes.

See also:
• REMOVAL [06/2012 - ]
• REMOVAL [06/2012 - ]