Air Conditioning System (Diagnostic Codes & Circuit Tests): Overview Lexus ES XV60

DESCRIPTION

The room temperature sensor (cooler thermistor) is installed in the instrument panel to detect the cabin temperature which is used to control the air conditioning system AUTO mode. The resistance of the room temperature sensor (cooler thermistor) changes in accordance with the cabin temperature. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.

The air conditioning amplifier assembly applies a voltage (5 V) to the room temperature sensor (cooler thermistor) and reads voltage changes due to changes in the resistance of the room temperature sensor (cooler thermistor).

Scheme 173

The ambient temperature sensor (thermistor assembly) is installed in front of the condenser to detect the ambient temperature which is used to control the air conditioning system AUTO mode. This sensor is connected to the air conditioning amplifier assembly and detects fluctuations in the ambient temperature. This data is used for controlling the cabin temperature. The sensor sends a signal to the air conditioning amplifier assembly. The resistance of the ambient temperature sensor (thermistor assembly) changes in accordance with the ambient temperature. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.

The air conditioning amplifier assembly applies a voltage (5 V) to the ambient temperature sensor (thermistor assembly) and reads voltage changes due to changes in the resistance of the ambient temperature sensor (thermistor assembly).

Scheme 174

The evaporator temperature sensor (No. 1 cooler thermistor) is installed on the evaporator in the air conditioner unit to detect the temperature of the cooled air that has passed through the evaporator and is used to control the air conditioning. It sends signals to the air conditioning amplifier assembly. The resistance of the evaporator temperature sensor (No. 1 cooler thermistor) changes in accordance with the temperature of the cooled air that has passed through the evaporator. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.

The air conditioning amplifier assembly applies voltage (5 V) to the evaporator temperature sensor (No. 1 cooler thermistor) and reads voltage changes as the resistance of the evaporator temperature sensor (No. 1 cooler thermistor) changes. This sensor is used for frost prevention.

Scheme 175

The smog ventilation sensor is installed on the front of the cooler condenser assembly to automatically control the air inlet mode (FRESH, FRESH/RECIRCULATION or RECIRCULATION).

This sensor detects CO and HC in exhaust gasses and transmits signals to the air conditioning amplifier assembly.

Scheme 176

SYSTEM DESCRIPTION

The ECM sends the engine speed signal to the air conditioning amplifier assembly via CAN communication.

The air conditioning amplifier assembly reads the difference between compressor speed and engine speed. When the difference becomes too large, the air conditioning amplifier assembly determines that the compressor is locked, and turns the magnetic clutch off.

Scheme 177

Scheme 178

1. PERFORM ACTIVE TEST USING TECHSTREAM Disconnect the a2 magnetic clutch assembly connector. TEXT IN ILLUSTRATION *a Front view of wire harness connector (to Magnetic Clutch Assembly) Install SST to the connector on the magnetic clutch relay side. SST: 09843-18040 Connect the Techstream to the DLC3. Start the engine. Turn the Techstream on. Enter the following menus: Body Electrical / Air Conditioner / Active Test. Measure the voltage according to the value(s) in the table below. NOTE: Take care that the connector or measurement tools do not contact the rotating parts of the engine. AIR CONDITIONER Tester Display Test Part Control Range Diagnostic Note Magnetic Clutch Relay A/C system operation OFF, ON - Standard Voltage Tester Connection Condition Specified Condition a2 - Body ground Engine is running Active Test above is being performed 11 to 14 V HINT: When performing the Active Test, voltage between 11 and 14 V is output for approximately 3 seconds. NG --> See step 8 OK: Go to next step
2. INSPECT MAGNET CLUTCH ASSEMBLY Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition a2-1 - Body ground 20°C (68°F) 3.8 to 4.2 ohms When connector terminal a2-1 is connected to a positive (+) battery terminal, check that the following occurs: 1) the magnetic clutch operating sound can be heard, and 2) the magnetic clutch hub and rotor lock. TEXT IN ILLUSTRATION *a Component without harness connected (Magnetic Clutch Assembly) NG --> See step 9 OK: Go to next step
3. INSPECT COOLER COMPRESSOR ASSEMBLY (A/C LOCK SENSOR) Disconnect the D65 cooler compressor assembly (A/C lock sensor) connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition D65-1 (SSR+) - D65-2 (SSR-) 20°C (68°F) 160 to 320 ohms TEXT IN ILLUSTRATION *a Component without harness connected (Cooler Compressor Assembly (A/C Lock Sensor)) NG --> See step 7 OK: Go to next step
4. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - COOLER COMPRESSOR ASSEMBLY (A/C LOCK SENSOR)) Disconnect the H54 air conditioning amplifier assembly connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition H54-8 (LOCK) - D65-1 (SSR+) Always Below 1 ohms H54-13 (SG-2) - D65-2 (SSR-) Always Below 1 ohms H54-8 (LOCK) - Body ground Always 10 kohms or higher H54-13 (SG-2) - Body ground Always 10 kohms or higher Result Result Proceed to NG A OK (When troubleshooting according to Problem Symptoms Table) B OK (When troubleshooting according to the DTC) C B --> See step 5 C --> See step 6 A --> REPAIR OR REPLACE HARNESS OR CONNECTOR
5. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to «PROBLEM SYMPTOMS TABLE [06/2012 - ]»(ref-598464-S25253580382014021400000)
6. REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to «REMOVAL [06/2012 - ]»(/lexus/es/xv60-2012-2015/remont/automatic-hvac-system/#air-conditioning-system-service-information)
7. REPLACE COOLER COMPRESSOR ASSEMBLY (A/C LOCK SENSOR). Refer to «REMOVAL [06/2012 - ]»(/lexus/es/xv60-2012-2015/remont/automatic-hvac-system/#air-conditioning-system-service-information)
8. GO TO AIR CONDITIONING COMPRESSOR MAGNETIC CLUTCH CIRCUIT. Refer to «Air Conditioning Compressor Magnetic Clutch Circuit»(ref-598664-S29083582012014021400000)
9. REPLACE MAGNET CLUTCH ASSEMBLY. Refer to «DISASSEMBLY [06/2012 - ]»(/lexus/es/xv60-2012-2015/remont/automatic-hvac-system/#air-conditioning-system-service-information)

This DTC is stored if refrigerant pressure on the high pressure side is extremely low (190 kPa (1.9 kgf/cm 2 , 28 psi) or less) or extremely high (3140 kPa (32.0 kgf/cm 2 , 455 psi) or more). The air conditioning pressure sensor, which is installed on the pipe on the high pressure side to detect refrigerant pressure, sends a refrigerant pressure signal to the air conditioning amplifier assembly. The air conditioning amplifier assembly converts this signal to a pressure value according to the sensor characteristics and uses it to control the compressor.

Scheme 179

The No. 1 air conditioning radiator damper servo sub-assembly (air mix (for front passenger side)) sends pulse signals to indicate the damper position to the air conditioning amplifier assembly. The air conditioning amplifier assembly activates the motor (normal or reverse) based on these signals to move the No. 1 air conditioning radiator damper servo sub-assembly (air mix (for front passenger side)) to the appropriate position. This adjusts the amount of air passing through the heater core after passing the evaporator and controls the temperature of the output air.

The air conditioning amplifier assembly communicates with the servo through a communication/driver IC and wiring assembly called the air conditioning harness assembly.

HINT

Confirm that no mechanical problem is present because this DTC can be output when either a damper link or the damper is mechanically locked.

Scheme 180

The No. 1 blower damper servo sub-assembly (air inlet) sends pulse signals to inform the air conditioning amplifier assembly of the damper position. The air conditioning amplifier assembly activates the motor (normal, reverse) based on the signals to move the air inlet mode selection No. 1 blower damper servo sub-assembly (air inlet) to any position, which controls the air inlet mode (FRESH, FRESH/RECIRCULATION, and RECIRCULATION).

The air conditioning amplifier assembly communicates with the servo through a communication/driver IC and wiring assembly called the air conditioning harness assembly.

HINT

Confirm that no mechanical problem is present because this DTC can be output when either a damper link or the damper is mechanically locked.

Scheme 181

The No. 1 air conditioning radiator damper servo sub-assembly (air outlet) sends pulse signals to inform the air conditioning amplifier assembly of the damper position. The air conditioning amplifier assembly activates the motor (normal, reverse) based on the signals to move the No. 1 air conditioning radiator damper servo sub-assembly (air outlet) to any position, which controls the air outlet switching.

The air conditioning amplifier assembly communicates with the servo through a communication/driver IC and wiring assembly called the air conditioning harness assembly.

HINT

Confirm that no mechanical problem is present because this DTC can be output when either a damper link or the damper is mechanically locked.

Scheme 182

The No. 2 air conditioning radiator damper servo sub-assembly (air mix (for driver side)) sends pulse signals to inform the air conditioning amplifier assembly of the damper position. The air conditioning amplifier assembly activates the motor (normal, reverse) based on the signals to move the No. 2 air conditioning radiator damper servo sub-assembly (air mix (for driver side)) to any position. As a result, the amount of air passing through the heater core after passing through the evaporator is adjusted, and the temperature of the air blowing toward the driver seat side is controlled.

The air conditioning amplifier assembly communicates with the servo through a communication/driver IC and wiring assembly called the air conditioning harness assembly.

HINT

Confirm that no mechanical problem is present because this DTC can be output when either a damper link or the damper is mechanically locked.

Scheme 183

In this circuit, the cooler compressor assembly (compressor solenoid) receives a refrigerant compression demand signal from the air conditioning amplifier assembly.

Based on this signal, the cooler compressor assembly (compressor solenoid) changes the amount of compressor output.

Scheme 184

The smog ventilation sensor is installed on the front of the condenser to automatically control the air inlet mode (FRESH, FRESH/RECIRCULATION or RECIRCULATION).

This sensor detects NOx in exhaust gasses and transmits signals to the air conditioning amplifier assembly.

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.

Scheme 185

The air conditioning harness assembly connects the air conditioning amplifier assembly and the servo motors. The air conditioning amplifier assembly supplies power and sends operation instructions to each servo motor through the air conditioning harness assembly. Each servo motor sends damper position information to the air conditioning amplifier assembly.

Scheme 186

The solar sensor (automatic light control sensor) is installed on the upper side of the instrument panel. It detects sunlight to control air conditioning AUTO mode. The output voltage from the solar sensor (automatic light control sensor) varies in accordance with the amount of sunlight. When the sunlight increases, the output voltage increases. As the sunlight decreases, the output voltage decreases. The air conditioning amplifier assembly detects changes in the output voltage from the solar sensor (automatic light control sensor).

Scheme 187

The accessory meter assembly communicates with the air conditioning amplifier assembly through the LIN communication system.

The accessory meter assembly receives an operation signal from the radio receiver assembly via AVC-LAN communication. It then converts this signal to a LIN communication signal and sends it to the air conditioning amplifier assembly.

Scheme 188

This DTC is stored if the amount of refrigerant in the air conditioning system is insufficient.

The air conditioning amplifier assembly receives the ambient temperature signal, refrigerant pressure signal etc. from various sensors.

Based on these signals, the air conditioning amplifier assembly detects the amount of refrigerant.

The A/C switch indicator is turned off and air conditioning system is stopped if the amount of refrigerant is insufficient in the cycle.

w/ Multi-display

1. The multi-media module receiver assembly or radio receiver assembly switch signals are sent to the air conditioning amplifier assembly via CAN communication.

w/o Multi-display

1. The radio receiver assembly switch signals are sent to the accessory meter assembly via AVC-LAN communication. The accessory meter assembly then sends these signals to the air conditioning amplifier assembly via LIN communication.

Scheme 189

Scheme 190

Scheme 191

1. w/ Navigation System or w/ Audio and Visual System (w/ Multi-display with Parking Assist Monitor System)
2. w/ Audio and Visual System (w/ Multi-display without Parking Assist Monitor System)
3. w/ Audio and Visual System (w/o Multi-display)

The blower motor with fan sub-assembly is operated by signals from the air conditioning amplifier assembly. Blower motor speed signals are transmitted in accordance with changes in the duty ratio.

Scheme 192

When the air conditioning amplifier assembly is turned on, a magnetic clutch on signal is sent from the MGC terminal of the air conditioning amplifier assembly. Then, the engine room junction block assembly turns on to operate the magnetic clutch assembly.

Scheme 193

The air conditioning amplifier assembly sends operation signals to the PTC HTR relays when quick heater assembly operation conditions are met. Based on the signals from the air conditioning amplifier assembly, the PTC HTR relays turn on, and power is supplied to the quick heater assembly installed in the air conditioning radiator assembly.

QUICK HEATER ASSEMBLY OPERATION CONDITION

Scheme 194

When the ECO mode switch (integration control and panel assembly) is turned on, the air conditioning amplifier assembly receives an ECO mode switch (integration control and panel assembly) ON signal and controls the air conditioning to enhance fuel efficiency.

Scheme 195

Scheme 196

1. READ VALUE USING TECHSTREAM Connect the Techstream to the DLC3. Turn the engine switch on (IG). Turn the Techstream on. Enter the following menus: Body Electrical / Air Conditioner / Data Test. Check the values by referring to the table below. AIR CONDITIONER Tester Display Measurement Item/Range Control Range Diagnostic Note ECO Switch ECO mode switch (integration control and panel assembly) / OFF or ON ECO mode switch (integration control and panel assembly) not turned: OFF - ECO mode switch (integration control and panel assembly) being turned and held at ECO position: ON OK ECO mode switch (integration control and panel assembly) condition displayed on the Techstream changes with the actual switch operation. NG --> See step 2 OK --> See step 5
2. INSPECT ECO MODE SWITCH (INTEGRATION CONTROL AND PANEL ASSEMBLY) Remove the ECO mode switch (integration control and panel assembly). Refer to «REMOVAL [06/2012 - ]»(ref-598611-S15967635902014021400000) . Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 4 (ECU) - 5 (E) ECO mode switch (integration control and panel assembly) not turned 10 kohms or higher 4 (ECU) - 5 (E) ECO mode switch (integration control and panel assembly) being turned and held at ECO position Below 1 ohms TEXT IN ILLUSTRATION *a Component without harness connected (ECO Mode Switch (Integration Control and Panel Assembly)) NG --> See step 6 OK: Go to next step
3. CHECK HARNESS AND CONNECTOR (ECO MODE SWITCH (INTEGRATION CONTROL AND PANEL ASSEMBLY) - AIR CONDITIONING AMPLIFIER ASSEMBLY) Disconnect the H54 air conditioning amplifier assembly connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition H54-4 (ECOS) - H71-4 (ECU) Always Below 1 ohms H54-4 (ECOS) - Body ground Always 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
4. CHECK HARNESS AND CONNECTOR (ECO MODE SWITCH (INTEGRATION CONTROL AND PANEL ASSEMBLY) - BODY GROUND) Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition H71-5 (E) - Body ground Always Below 1 ohms NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK --> See step 7
5. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to «PROBLEM SYMPTOMS TABLE [06/2012 - ]»(ref-598464-S25253580382014021400000)
6. REPLACE ECO MODE SWITCH (INTEGRATION CONTROL AND PANEL ASSEMBLY). Refer to «REMOVAL [06/2012 - ]»(ref-598611-S15967635902014021400000)
7. REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to «REMOVAL [06/2012 - ]»(/lexus/es/xv60-2012-2015/remont/automatic-hvac-system/#air-conditioning-system-service-information)

The main power source is supplied to the air conditioning amplifier assembly when the engine switch is turned on (IG).

The power is used for operating the air conditioning amplifier assembly, servo motors, etc.

Scheme 197

The back-up power source circuit for the air conditioning amplifier assembly is shown below. Power is supplied even when the engine switch is off. The power is used for diagnostic trouble code memory, etc.

Scheme 198

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