Air Conditioning (Diagnostics Codes & Circuit Tests): Overview Lexus HS I

DESCRIPTION

The room temperature sensor is installed in the instrument panel. It detects the cabin temperature to control air conditioning AUTO mode. The resistance of the room temperature sensor 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 voltage (5 V) to the room temperature sensor and reads voltage changes as the resistance of the room temperature sensor changes. This sensor also sends appropriate signals to the air conditioning amplifier assembly. The room temperature sensor is integrated with the room humidity sensor.

Scheme 96

The ambient temperature sensor is installed in front of the condenser. It detects the ambient temperature to control air conditioning 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 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 voltage (5 V) to the ambient temperature sensor and reads voltage changes as the resistance of the ambient temperature sensor changes.

Scheme 97

The evaporator temperature sensor is installed on the evaporator in the air conditioning unit to detect the cooled air temperature that has passed through the evaporator and to control the air conditioning. It sends appropriate signals to the air conditioning amplifier assembly. The resistance of the evaporator temperature sensor changes in accordance with the cooled air temperature 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 and reads voltage changes as the resistance of the evaporator temperature sensor changes. This sensor is used for frost prevention.

Scheme 98

Scheme 99

1. READ VALUE USING TECHSTREAM Connect the Techstream to the DLC3. Turn the power switch on (IG). Turn the Techstream on. Enter the following menus: Body Electrical / Air Conditioner / Data List. Check the value(s) by referring to the table below. AIR CONDITIONER Tester Display Measurement Item/Range Normal Condition Evaporator Fin Thermistor Evaporator temperature sensor / Min.: -29.7°C (-21.46°F) Max.: 59.55°C (139.19°F) Actual evaporator temperature displayed OK The display is as specified in the Normal Condition column. Result Result Proceed to NG A OK (When troubleshooting according to Problem Symptoms Table) B OK (When troubleshooting according to the DTC) C C --> See step 4 B --> See step 5 A: Go to next step
2. INSPECT EVAPORATOR TEMPERATURE SENSOR Remove the evaporator temperature sensor. Disconnect the evaporator temperature sensor connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 1 - 2 -10°C (14°F) 7.30 to 9.10 kohms 1 - 2 -5°C (23°F) 5.65 to 6.95 kohms 1 - 2 0°C (32°F) 4.40 to 5.35 kohms 1 - 2 5°C (41°F) 3.40 to 4.15 kohms 1 - 2 10°C (50°F) 2.70 to 3.25 kohms 1 - 2 15°C (59°F) 2.14 to 2.58 kohms 1 - 2 20°C (68°F) 1.71 to 2.05 kohms 1 - 2 25°C (77°F) 1.38 to 1.64 kohms 1 - 2 30°C (86°F) 1.11 to 1.32 kohms NOTE: Hold the sensor only by its connector. Touching the sensor may change the resistance value. When measuring, the sensor temperature must be the same as the ambient temperature. HINT: As the temperature increases, the resistance decreases (see the graph (Scheme 99) ). TEXT IN ILLUSTRATION *1 Component without harness connected (Evaporator Temperature Sensor) *2 Sensing Portion NG --> See step 7 OK: Go to next step
3. INSPECT AIR CONDITIONING HARNESS (A/C AMPLIFIER ASSEMBLY - EVAPORATOR TEMPERATURE SENSOR) Remove the air conditioning harness. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition z1-6 (TEA) - 2 Always Below 1 ohms z1-5 (SGA) - 1 Always Below 1 ohms z1-6 (TEA) - Body ground Always 10 kohms or higher z1-5 (SGA) - Body ground Always 10 kohms or higher NG --> See step 8 OK --> See step 6
4. REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to «REMOVAL»(/lexus/hs/i-2009-2012/remont/automatic-hvac-system/#air-conditioning-service-information)
5. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to «PROBLEM SYMPTOMS TABLE»(ref-398247-S14990846712011051600000)
6. REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to «REMOVAL»(/lexus/hs/i-2009-2012/remont/automatic-hvac-system/#air-conditioning-service-information)
7. REPLACE EVAPORATOR TEMPERATURE SENSOR. Refer to «REMOVAL»(/lexus/hs/i-2009-2012/remont/automatic-hvac-system/#air-conditioning-service-information)
8. REPLACE AIR CONDITIONING HARNESS. Refer to «DISASSEMBLY»(/lexus/hs/i-2009-2012/remont/automatic-hvac-system/#air-conditioning-service-information)

This DTC is stored when refrigerant pressure on the high pressure side is extremely low (0.19 MPa (2.0 kgf/cm 2 , 28 psi) or less) or extremely high (3.14 MPa (32.0 kgf/cm 2 , 455 psi) or more). The A/C pressure sensor is installed on the high pressure line. It detects refrigerant pressure to output 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 to control the compressor.

Scheme 100

Scheme 101

Scheme 102

1. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT) Disconnect the A/C pressure sensor connector. Measure the voltage according to the value(s) in the table below. Standard Voltage Tester Connection Switch Condition Specified Condition A28-3 (+) - Body ground Power switch on (IG) 4.75 to 5.25 V NG --> See step 5 OK: Go to next step
2. CHECK HARNESS AND CONNECTOR (GROUND CIRCUIT) Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition A28-1 (-) - Body ground Always Below 1 ohms NG --> See step 6 OK: Go to next step
3. INSPECT A/C PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT) Reconnect the A/C pressure sensor connector. Remove the air conditioning amplifier assembly with the connectors still connected. Measure the voltage according to the value(s) in the table below. Standard Voltage Tester Connection Condition Specified Condition F48-16 (PRE) - Body ground Power switch on (IG) (A/C switch: off) 0.7 to 4.8 V HINT: If the voltage is not as specified, there may be a malfunction in the air conditioning amplifier assembly, A/C pressure sensor or wire harness. It is also possible that the amount of refrigerant may not be appropriate. TEXT IN ILLUSTRATION *1 Component with harness connected (Air conditioning amplifier assembly) NG --> See step 7 OK: Go to next step
4. INSPECT A/C PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT) Measure the voltage when the following conditions are met: Item Condition Vehicle Doors Fully open Compressor speed 5200 rpm Temperature Setting MAX COLD Blower Speed HI A/C Switch on R/F Switch RECIRCULATION Interior Temperature 25 to 35°C (77 to 95°F) NOTE: If refrigerant pressure on the high pressure line becomes extremely high during the inspection (if the voltage exceeds 4.84 V), the fail-safe function stops compressor operation. Therefore, measure the voltage before the fail-safe function operates. It is necessary to measure the voltage over a period of time (approximately 10 minutes) because the problem symptom may recur after a while. HINT: When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to signals from the ambient temperature sensor and the evaporator temperature sensor to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment. Measure the voltage according to the value(s) in the table below. Standard Voltage Tester Connection Condition Specified Condition F48-16 (PRE) - Body ground Power switch on (IG) (A/C: on) 0.7 to 4.8 V Result Result Proceed to OK (When troubleshooting according to the DTC) A OK (When troubleshooting according to Problem Symptoms Table) B NG C TEXT IN ILLUSTRATION *1 Component with harness connected (Air conditioning amplifier assembly) C --> See step 13 B --> See step 19 A --> See step 20
5. CHECK HARNESS AND CONNECTOR (A/C AMPLIFIER ASSEMBLY - A/C PRESSURE SENSOR) Disconnect the air conditioning amplifier assembly connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition A28-3 (+) - F47-10 (S5-3) Always Below 1 ohms F47-10 (S5-3) - Body ground Always 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK --> See step 20
6. CHECK HARNESS AND CONNECTOR (A/C AMPLIFIER ASSEMBLY - A/C PRESSURE SENSOR) Disconnect the air conditioning amplifier assembly connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition A28-1 (-) - F47-13 (SG-2) Always Below 1 ohms F47-13 (SG-2) - Body ground Always 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK --> See step 20
7. CHECK HARNESS AND CONNECTOR (A/C AMPLIFIER ASSEMBLY - A/C PRESSURE SENSOR) Disconnect the air conditioning amplifier assembly connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition A28-2 (PR) - F48-16 (PRE) Always Below 1 ohms F48-16 (PRE) - Body ground Always 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
8. CHECK FOR A/C SYSTEM LEAK Install the manifold gauge set. Recover the refrigerant from the A/C system using a refrigerant recovery unit. Evacuate the A/C system and check that vacuum can be maintained. OK Vacuum can be maintained in the A/C system. HINT: If vacuum cannot be maintained in the A/C system, there may be a refrigerant leak. In this case, it is necessary to repair or replace the leaking part of the A/C system. NG --> See step 12 OK: Go to next step
9. CHARGE REFRIGERANT Add an appropriate amount of refrigerant. Refer to «REPLACEMENT»(/lexus/hs/i-2009-2012/remont/automatic-hvac-system/#air-conditioning-service-information) . NEXT: Go to next step
10. RECHECK FOR DTC Recheck for the DTC when the following conditions are met: Item Condition Vehicle Doors Fully open Compressor Speed 5200 rpm Temperature Setting MAX COLD Blower Speed HI A/C Switch on R/F Switch RECIRCULATION Interior Temperature 25 to 35°C (77 to 95°F) NOTE: If refrigerant pressure on the high pressure line is excessive, this DTC will be stored. Therefore, it is necessary to measure the voltage over a period of time (approximately 10 minutes) because this DTC may be stored after the A/C has been operating for a while. HINT: When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to signals from the ambient temperature sensor and the evaporator temperature sensor to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment. Result Result Proceed to DTC B1423/23 is output A DTC B1423/23 is not output B NOTE: If the DTC was stored due to an insufficient or excessive amount of refrigerant, the problem may have been solved after performing the previous step. However, the root cause of insufficient refrigerant may be refrigerant leaks. The root cause of excessive refrigerant may be adding refrigerant when the level was insufficient. Therefore, identify and repair any refrigerant leaks as necessary. B --> END A: Go to next step
11. INSPECT A/C PRESSURE SENSOR Install the manifold gauge set. Reconnect the A/C pressure sensor connector. Turn the power switch on (IG). Measure the voltage according to the value(s) in the table below. Standard Voltage Tester Connection Condition Specified Condition F48-16 (PRE) - F47-13 (SG-2)*1 Refrigerant pressure: Normal pressure (less than 3.187 MPa [462 psi] and more than 0.39 MPa [57 psi]) 1.0 to 4.9 V HINT: The A/C pressure sensor power source voltage is 5 V. TEXT IN ILLUSTRATION *1 Component with harness connected (Air conditioning amplifier assembly) NG --> See step 24 OK --> See step 20
12. REPAIR A/C SYSTEM LEAK Identify the area where refrigerant leaks from. Refer to «REPLACEMENT»(/lexus/hs/i-2009-2012/remont/automatic-hvac-system/#air-conditioning-service-information) . Repair the identified area of the A/C system. Evacuate the A/C system. NEXT --> See step 21
13. INSPECT COOLING FAN SYSTEM Check that the cooling fan(s) operates normally. HINT: Refer to Cooling Fan Circuit. Refer to «Cooling Fan Circuit»(ref-398243-S41232609942011051600000) . NG --> REPAIR COOLING FAN SYSTEM OK: Go to next step
14. CHARGE REFRIGERANT Use a refrigerant recovery unit to recover refrigerant. Evacuate the A/C system. Add an appropriate amount of refrigerant. Refer to «REPLACEMENT»(/lexus/hs/i-2009-2012/remont/automatic-hvac-system/#air-conditioning-service-information) . HINT: If refrigerant is added and the system has not been properly evacuated (insufficient vacuum time), moisture in the air remaining in the system will freeze in the expansion valve, blocking the flow on the high pressure side. Therefore, recover the refrigerant and properly evacuate the system. Add an appropriate amount of refrigerant, and check for DTCs. NEXT: Go to next step
15. RECHECK FOR DTC Recheck for the DTC when the following conditions are met: Item Condition Vehicle Doors Fully open Compressor Speed 5200 rpm Temperature Setting MAX COLD Blower Speed HI A/C Switch on R/F Switch RECIRCULATION Interior Temperature 25 to 35°C (77 to 95°F) NOTE: If refrigerant pressure on the high pressure line is excessive, this DTC will be stored. Therefore, it is necessary to measure the voltage over a period of time (approximately 10 minutes) because DTC may be stored after the A/C has been operating for a while. HINT: When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to signals from the ambient temperature sensor and the evaporator temperature sensor to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment. If refrigerant is added and the system has not been properly evacuated (insufficient vacuum time), moisture in the air remaining in the system will freeze in the expansion valve, blocking the flow on the high pressure side. Therefore, recover the refrigerant and properly evacuate the system. Add an appropriate amount of refrigerant, and check for the DTC. If the DTC is not output, it indicates that the cooler dryer in the condenser is not able to absorb moisture in the refrigerant. In this case, to complete the repair, it is necessary to replace the cooler dryer. Result Result Proceed to DTC B1423/23 is output A DTC B1423/23 is not output B B --> See step 22 A: Go to next step
16. REPLACE EXPANSION VALVE Replace the expansion valve with a new or a known good one. Refer to «DISASSEMBLY»(/lexus/hs/i-2009-2012/remont/automatic-hvac-system/#air-conditioning-service-information) . HINT: Replace the expansion valve with a new or a known good one because the expansion valve is either stuck or clogged. NEXT: Go to next step
17. CHARGE REFRIGERANT Add an appropriate amount of refrigerant. Refer to «REPLACEMENT»(/lexus/hs/i-2009-2012/remont/automatic-hvac-system/#air-conditioning-service-information) . NEXT: Go to next step
18. RECHECK FOR DTC Recheck for the DTC when the following conditions are met: Item Condition Vehicle Doors Fully open Compressor Speed 5200 rpm Temperature Setting MAX COLD Blower Speed HI A/C Switch on R/F Switch RECIRCULATION Interior Temperature 25 to 35°C (77 to 95°F) NOTE: If refrigerant pressure on the high pressure line is excessive, this DTC will be stored. Therefore, it is necessary to measure the voltage over a period of time (approximately 10 minutes) because this DTC may be stored after the A/C has been operating for a while. HINT: When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to signals from the ambient temperature sensor and the evaporator temperature sensor to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment. If refrigerant pressure is not normal after replacing the expansion valve with a new or a known good one, the condenser or pipes may be clogged with dirt, dust or other contaminants. In this case, clean or replace the condenser or pipes. Result Result Proceed to DTC B1423/23 is not output A DTC B1423/23 is output B B --> See step 23 A --> END
19. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to «PROBLEM SYMPTOMS TABLE»(ref-398247-S14990846712011051600000)
20. REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to «REMOVAL»(/lexus/hs/i-2009-2012/remont/automatic-hvac-system/#air-conditioning-service-information)
21. CHARGE REFRIGERANT. Refer to «REPLACEMENT»(/lexus/hs/i-2009-2012/remont/automatic-hvac-system/#air-conditioning-service-information)
22. REPLACE COOLER DRYER. Refer to «DISASSEMBLY»(/lexus/hs/i-2009-2012/remont/automatic-hvac-system/#air-conditioning-service-information)
23. REPLACE CONDENSER. Refer to «REMOVAL»(/lexus/hs/i-2009-2012/remont/automatic-hvac-system/#air-conditioning-service-information)
24. REPLACE A/C PRESSURE SENSOR Replace the A/C pressure sensor. Refer to «REMOVAL»(/lexus/hs/i-2009-2012/remont/automatic-hvac-system/#air-conditioning-service-information) . HINT: Since the A/C pressure sensor cannot be inspected while it is removed from the vehicle, replace the A/C pressure sensor with a new or a known good one and check that the condition returns to normal. NEXT: Go to next step
25. RECHECK FOR DTC Recheck for the DTC when the following conditions are met: Item Condition Vehicle Doors Fully open Compressor Speed 5200 rpm Temperature Setting MAX COLD Blower Speed HI A/C Switch on R/F Switch RECIRCULATION Interior Temperature 25 to 35°C (77 to 95°F) NOTE: If refrigerant pressure on the high pressure line is excessive, this DTC will be stored. Therefore, it is necessary to measure the voltage over a period of time (approximately 10 minutes) because this DTC may be stored after the A/C has been operating for a while. HINT: When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to signals from the ambient temperature sensor and the evaporator temperature sensor to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment. Result Result Proceed to DTC B1423/23 is not output A DTC B1423/23 is output B B --> See step 20 A --> END

The air mix control servo motor 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 air mix damper (front passenger 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 passenger 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.

HINT

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

Scheme 103

The air inlet control servo motor 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 air inlet mode selection air inlet control damper to any position, which controls the intake air settings (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.

HINT

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

Scheme 104

The air outlet control servo motor 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 mode damper 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.

HINT

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

Scheme 105

The air mix control servo motor 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 air mix damper (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 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.

HINT

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

Scheme 106

The room humidity sensor detects cabin humidity. The voltage of the room humidity sensor changes in accordance with cabin humidity. The air conditioning amplifier assembly reads changes in the room humidity sensor.

The room humidity sensor is integrated with the room temperature sensor.

Scheme 107

1. READ VALUE USING TECHSTREAM Connect the Techstream to the DLC3. Turn the power switch on (IG). Turn the Techstream on. Enter the following menus: Body Electrical / Air Conditioner / Data List. Check the value(s) by referring to the table below. AIR CONDITIONER Tester Display Measurement Item/Range Normal Condition Humidity Sensor Room humidity sensor / Min.: 0%, Max.: 100% Actual cabin humidity displayed OK The display is as specified in the Normal Condition column. Result Result Proceed to NG A OK (When troubleshooting according to Problem Symptoms Table) B OK (When troubleshooting according to the DTC) C C --> See step 6 B --> See step 5 A: Go to next step
2. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT) Disconnect the room humidity sensor connector. Measure the voltage according to the value(s) in the table below. Standard Voltage Tester Connection Condition Specified Condition F25-4 (S5) - F25-2 (-) Power switch on (IG) 4.5 to 5.5 V NG --> See step 4 OK: Go to next step
3. INSPECT ROOM HUMIDITY SENSOR Reconnect the room humidity sensor connector. Turn the power switch on (IG). Measure the voltage according to the value(s) in the table below. Standard Voltage Tester Connection Condition Specified Condition F25-3 (RH) - F25-2 (-) at 25°C (77°F) Humidity 10% 0.7 to 1.08 V F25-3 (RH) - F25-2 (-) at 25°C (77°F) Humidity 20% 0.72 to 1.57 V F25-3 (RH) - F25-2 (-) at 25°C (77°F) Humidity 30% 1.13 to 1.95 V F25-3 (RH) - F25-2 (-) at 25°C (77°F) Humidity 40% 1.61 to 2.24 V F25-3 (RH) - F25-2 (-) at 25°C (77°F) Humidity 50% 1.99 to 2.46 V F25-3 (RH) - F25-2 (-) at 25°C (77°F) Humidity 60% 2.26 to 2.66 V F25-3 (RH) - F25-2 (-) at 25°C (77°F) Humidity 70% 2.48 to 2.85 V F25-3 (RH) - F25-2 (-) at 25°C (77°F) Humidity 80% 2.68 to 3.04 V F25-3 (RH) - F25-2 (-) at 25°C (77°F) Humidity 90% 2.87 to 3.05 V NOTE: Do not touch the room humidity sensor because it may be affected by body temperature and may not work properly. Hold the sensor only by its connector. The output voltage at the ambient temperature 25°C (77°F) is shown above. HINT: As the humidity increases, the voltage increases (see the graph (Scheme 107) ). TEXT IN ILLUSTRATION *1 Component with harness connected (Room Humidity Sensor) NG --> See step 7 OK: Go to next step
4. CHECK HARNESS AND CONNECTOR (ROOM HUMIDITY SENSOR - AIR CONDITIONING AMPLIFIER ASSEMBLY) Disconnect the air conditioning amplifier assembly connector. Disconnect the room humidity sensor connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition F47-31 (S5-4) - F25-4 (S5) Always Below 1 ohms F47-28 (RH) - F25-3 (RH) Always Below 1 ohms F47-34 (SG-1) - F25-2 (-) Always Below 1 ohms F47-31 (S5-4) - Body ground Always 10 kohms or higher F47-28 (RH) - Body ground Always 10 kohms or higher F47-34 (SG-1) - Body ground Always 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK --> See step 6
5. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to «PROBLEM SYMPTOMS TABLE»(ref-398247-S14990846712011051600000)
6. REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to «REMOVAL»(/lexus/hs/i-2009-2012/remont/automatic-hvac-system/#air-conditioning-service-information)
7. REPLACE ROOM HUMIDITY SENSOR. Refer to «REMOVAL»(/lexus/hs/i-2009-2012/remont/automatic-hvac-system/#air-conditioning-service-information)

The A/C inverter assembly monitors power voltage from the main battery in the circuit. It stops compressor control and outputs the DTC when the monitored voltage is outside the specified range.

The output DTC is memorized as a history DTC. Compressor control may not resume unless the power switch is turned off.

Scheme 108

The inverter in the compressor with motor assembly outputs high-voltage to operate the motor. If there is an open or short in the output circuit, the ECU will stop compressor operation and output the DTC. The output DTC will be memorized as a history DTC. The compressor operation remains stopped until both the history and current DTCs are cleared.

The inverter activation signal is sent to the compressor with motor assembly from the power management control ECU. Compressor control is stopped and the DTC is stored if there is an open or short in the signal circuit.

The temperature sensor of the compressor with motor assembly detects inverter temperature.

If the temperature exceeds the maximum, the compressor with motor assembly stops compressor operation, and this DTC will be stored.

The compressor with motor assembly stops compressor control and outputs this DTC if the rotation load is too large or too small while controlling motor rotation in the compressor with motor assembly.

Possible causes are refrigerant gas leakage, overcharged refrigerant gas, insufficient cooling because of a condenser fan circuit malfunction, or compressor lock.

The compressor with motor assembly monitors the controlling power voltage in the circuit. It stops the compressor circuit and outputs the DTC when the monitored voltage is outside the specified range.

The output DTC is memorized as a history DTC. The compressor control may not resume unless the power switch is turned off.

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

Scheme 109

Scheme 110

Scheme 111

1. INSPECT AIR CONDITIONING AMPLIFIER ASSEMBLY Remove the air conditioning amplifier assembly with the connectors still connected. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition z1-2 (BUS G) - Body ground Always Below 1 ohms TEXT IN ILLUSTRATION *1 Component with harness connected (Air conditioning amplifier assembly) NG --> See step 4 OK: Go to next step
2. INSPECT AIR CONDITIONING AMPLIFIER ASSEMBLY Measure the voltage and check for pulses according to the value(s) in the table below. Standard Tester Connection Condition Specified Condition z1-4 (B BUS) - z1-2 (BUS G) Power switch off 11 to 14 V z1-3 (BUS) - z1-2 (BUS G) Power switch on (IG) Pulse generation TEXT IN ILLUSTRATION *1 Component with harness connected (Air conditioning amplifier assembly) NG --> See step 5 OK --> See step 3
3. REPLACE AIR CONDITIONING HARNESS. Refer to «DISASSEMBLY»(/lexus/hs/i-2009-2012/remont/automatic-hvac-system/#air-conditioning-service-information)
4. REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to «REMOVAL»(/lexus/hs/i-2009-2012/remont/automatic-hvac-system/#air-conditioning-service-information)
5. REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to «REMOVAL»(/lexus/hs/i-2009-2012/remont/automatic-hvac-system/#air-conditioning-service-information)

The power management control ECU and compressor with motor assembly transmit information to one another via a communication line. Compressor control is stopped and the DTC is output if communication information is cut off or abnormal information occurs.

The DTC is also detected if high-voltage power supplied from the inverter with converter assembly to the compressor control circuit is shut off.

The output DTC is memorized as a history DTC.

Note. Depending on the timing of the power supply to the 12 V power supply circuit and high-voltage circuit when the power switch is turned on (READY), an abnormal information signal may be output, causing this DTC to be stored. If the output DTC is a code that was memorized in the past, check the fuses and wire harnesses. If there is no malfunction, clear the DTC.

The plasmacluster (ion generator) operates in conjunction with blower switch operation.

Scheme 112

The solar 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 varies in accordance with the amount of sunlight. When the amount of 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.

Scheme 113

The DTC is stored if there is insulation trouble with the high-voltage circuits in the air conditioning system. Possible causes are poor insulation in the compressor with motor assembly, or mixing of any oil other than ND-OIL 11 in the refrigerant cycle.

The motor driven with high-voltage is built into the electrical compressor and is cooled directly with refrigerant. Compressor oil (ND-OIL 11) with high insulation performance is used because a leakage of electrical power may occur if regular compressor oil (other than ND-OIL 11) is used.

w/ Navigation System

1. Integration control and panel assembly switch signals are sent to the air conditioning amplifier assembly via LIN communication. The air conditioning amplifier assembly then sends these signals to the display and navigation module display via CAN communication.

w/o Navigation System

1. Integration control and panel assembly switch signals are sent to the air conditioning amplifier assembly via LIN communication. The air conditioning amplifier assembly then sends these signals to the multi-display via LIN communication.

Scheme 114

Scheme 115

1. w/ Navigation System
2. w/o Navigation System

The blower motor 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 116

The heater water pump assembly sends engine coolant to the heater core assembly while the engine is stopped to prevent heater effectiveness from becoming low. Directed by the air conditioning amplifier assembly, the power management control ECU operates the water pump relay and drives the heater water pump assembly.

Scheme 117

The rear blower motor is operated by signals from the air conditioning amplifier. Rear blower motor speed signals are transmitted in accordance with changes in the duty ratio.

HINT

The rear blower motor operates when the rear cooler switch is on and the front blower switch is in the FACE or B/L position.

Scheme 118

The ECO MODE switch (combination switch assembly) is installed on the instrument panel on the driver side. When the ECO MODE switch (combination switch assembly) is turned on, the air conditioning amplifier assembly receives an ECO MODE switch (combination switch assembly) ON signal and controls the air conditioning to enhance fuel efficiency.

When the heater is on, the engine ON request coolant temperature will be set to a lower level. Thus, the length of time that the engine operates to generate the heat necessary to operate the heater will be limited. When the engine coolant temperature drops, the amount of air flow of the blower motor will also decrease. If FOOT/DEF or DEF is selected, or if the temperature is set to MAX HOT, the fuel efficiency control due to the ECO MODE switch (combination switch assembly) operation will be canceled.

When the air conditioning is used to cool the vehicle, the power consumption of the compressor will be limited. Initially, the air conditioning will operate normally until the cabin temperature stabilizes. After the cabin temperature stabilizes, the power consumption of the compressor will be limited while stabilizing the cabin temperature. If the temperature is set to MAX COOL, the fuel efficiency control due to the ECO MODE switch (combination switch assembly) operation will be canceled.

Scheme 119

Scheme 120

1. READ VALUE USING TECHSTREAM Connect the Techstream to the DLC3. Turn the power 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 ECO Switch ECO MODE switch / OFF or ON OFF: ECO MODE switch not pressed ON: ECO MODE switch pressed OK ECO MODE switch condition displayed on the Techstream changes with the actual switch operation. NG --> See step 2 OK --> See step 4
2. CHECK HARNESS AND CONNECTOR (ECO MODE SWITCH - AIR CONDITIONING AMPLIFIER ASSEMBLY) Disconnect the connector from the ECO MODE switch (combination switch assembly). Disconnect the connector from the air conditioning amplifier assembly. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition F18-5 (ECO) - F47-9 (ECON) Always Below 1 ohms F18-5 (ECO) - Body ground Always 10 kohms or higher F18-4 (E) - F47-35 (SG-4) Always Below 1 ohms F18-4 (E) - Body ground Always 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
3. INSPECT ECO MODE SWITCH (COMBINATION SWITCH ASSEMBLY) Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 4 (E) - 5 (ECO) ECO MODE switch off (when switch is not pressed) 10 kohms or higher ECO MODE switch on (when switch is pressed) Below 1 ohms TEXT IN ILLUSTRATION *1 Component without harness connected (ECO MODE Switch (Combination Switch Assembly)) NG --> See step 5 OK --> See step 4
4. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to «PROBLEM SYMPTOMS TABLE»(ref-398247-S14990846712011051600000)
5. REPLACE ECO MODE SWITCH (COMBINATION SWITCH ASSEMBLY). Refer to «REMOVAL»(ref-398232-S23471497322011051600000)

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

The power source is used for operating the air conditioning amplifier assembly and servo motor, etc.

Scheme 121

The back-up power source circuit for the air conditioning amplifier assembly is shown below. Power is supplied even when the power switch is turned off. The power is used for DTC memory etc.

Scheme 122

See also:
• REMOVAL
• REMOVAL
• REMOVAL