Air Conditioning System (Diagnostic Codes & Circuit Tests): Overview Lexus IS II facelift 2

Scheme 18

Scheme 19

Scheme 20

1. ACTUATOR CHECK Start the engine and warm it up. Perform the indicator check. Refer to «CHECK MODE PROCEDURE [08/2012 - ]»(ref-606501-S27469038942014032500000). Push the recirculation/fresh switch to perform the actuator check. HINT: Be sure to perform the actuator check after starting the engine. As the actuator check is repeated from steps 1 to 10 at 1 second intervals, check the temperature and air flow visually and by hand. HINT: The display blinks at 1 second intervals in step operation. As an example, the illustration shows that display code 5 is output. Push the OFF switch to finish panel diagnosis. Push the AUTO switch to enter the sensor check mode. Step No. Display Code Conditions Blower Level Air Mix Damper Airflow Vent Air Inlet Damper Cool Air By-pass Damper Compressor 1 0 0 0% open FACE FRESH -14% OFF 2 1 1 0% open FACE FRESH -14% OFF 3 2 17 0% open FACE RECIRCULATION / FRESH -14% ON 4 3 17 0% open FACE RECIRCULATION 113.50% ON 5 4 17 50% open B/L RECIRCULATION 113.50% ON 6 5 17 50% open B/L RECIRCULATION 113.50% ON 7 6 17 50% open FOOT FRESH 113.50% ON 8 7 17 100% open FOOT-0 FRESH 113.50% ON 9 8 17 100% open F/D FRESH 113.50% ON 10 9 31 100% open DEF FRESH 113.50% ON If the steps are difficult to read because they change automatically, push the driver side TEMP up switch to display the steps one at a time so that they can be read easily. The items are displayed step by step each time the driver side TEMP up switch is pushed. HINT: Push the OFF switch to finish panel diagnosis. Push the recirculation/fresh switch to enter the actuator check mode.

DESCRIPTION

This sensor detects the cabin temperature that is used as the basis for temperature control and sends a signal to the A/C amplifier.

Scheme 21

The ambient temperature sensor is installed in front of the condenser to detect the ambient temperature which is used to control the air conditioner "AUTO" mode. This sensor connected to the ECM and detects fluctuations in the ambient temperature. This data is used for controlling the cabin temperature. The sensor sends a signal to the A/C amplifier via the ECM. 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 ECM applies voltage (5 V) to the ambient temperature sensor and reads voltage changes as the resistance of the ambient temperature sensor changes. The ECM sends the signal to the A/C amplifier via CAN and body multiplex communication.

Scheme 22

The evaporator temperature sensor (A/C thermistor) is installed on the evaporator in the air conditioner unit. It detects the temperature of the cooled air that has passed through the evaporator and its signal is used to control the air conditioning. It sends a signal to the A/C amplifier. The resistance of the evaporator temperature sensor (A/C 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 A/C amplifier applies voltage (5 V) to the evaporator temperature sensor (A/C thermistor) and reads voltage changes as the resistance of the evaporator temperature sensor (A/C thermistor) changes. This sensor is used to prevent the evaporator from freezing.

Scheme 23

The smog ventilation sensor, which is installed on the front of the condenser, is used for automatic air inlet control. This sensor detects CO and HC in the emission gas and transmits signals to the A/C amplifier.

Scheme 24

This sensor sends 1 pulse per engine revolution to the ECM.

If the ratio between engine and compressor speed deviates 20% or more compared to normal operation, the ECM turns the cooler compressor off and the indicator blinks at approximately 1 second intervals.

The ECM informs the A/C amplifier of the operation condition of the cooler compressor through multiplex communication (CAN and BEAN).

Scheme 25

This DTC is output when refrigerant pressure 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 pressure sensor, which is installed on the pipe of the high pressure side to detect refrigerant pressure, outputs a refrigerant pressure signal to the A/C amplifier. The A/C amplifier converts this signal to pressure according to the sensor characteristics to control the compressor.

HINT

Be sure to check the refrigerant volume first when this DTC is output because this DTC can also be output if there is no refrigerant in the system.

Scheme 26

Scheme 27

1. CHECK REFRIGERANT Check the sight glass of the cooler unit refrigerant liquid pipe. Prepare the vehicle according to the chart below. Item Condition Vehicle Doors Fully open Temperature Setting MAX COLD Blower Speed HI A/C ON Compare the sight glass to the following chart. Item Symptom Amount of Refrigerant Corrective Actions 1 Bubbles visible Insufficient* Check for gas leakage and repair if necessary Add refrigerant until bubbles disappear 2 No bubbles visible Empty, insufficient, or excessive Refer to 3 and 4 3 No temperature difference between compressor inlet and outlet Empty or nearly empty Check for gas leakage with gas leak detector and repair if necessary Evacuate A/C system and recharge with proper amount of refrigerant 4 Considerable temperature difference between compressor inlet and outlet Proper or excessive Refer to 5 and 6 5 Immediately after air conditioning is turned OFF, refrigerant clears Excessive Recover refrigerant Evacuate A/C system and recharge with proper amount of refrigerant 6 Immediately after air conditioning is turned OFF, refrigerant foams and then becomes clear Proper - * : Bubbles in the sight glass with the vehicle interior temperature above 35°C (95°F) can be considered normal if cooling is sufficient. NG --> CHARGE REFRIGERANT OK: Go to next step
2. CHECK WIRE HARNESS (PRESSURE SENSOR - A/C AMPLIFIER) Disconnect the pressure sensor connector. Disconnect the A/C amplifier connector. Measure the resistance according to the value(s) in the table below. Standard resistance Tester Connection Condition Specified Condition B7-2 (PR) - J58-13 (PRE) Always Below 1 ohms B7-3 (+) - J58-26 (S5-2) Always Below 1 ohms B7-1 (-) - J58-38 (SG-2) Always Below 1 ohms J58-13 (PRE) - Body ground Always 10 kohms or higher J58-26 (S5-2) - Body ground Always 10 kohms or higher J58-38 (SG-2) - Body ground Always 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
3. INSPECT PRESSURE SENSOR Install the manifold gauge set. Refer to «ON-VEHICLE INSPECTION [08/2012 - ]»(/lexus/is/ii-facelift-2-2010-2016/remont/automatic-hvac-system/#air-conditioning-system-service-information) . Connect the three 1.5 V dry cell batterie's positive (+) lead to terminal 3 and the negative (-) lead to terminal 1. Then connect the voltmeter's positive (+) lead to terminal 2 and the negative (-) lead to terminal 1. Measure the voltage. OK The voltage changes according to refrigerant pressure, as shown in the graph. Result Result Proceed to NG A OK (When troubleshooting according to the DTC) B OK (When troubleshooting according to the PROBLEM SYMPTOMS TABLE) C B --> REPLACE AIR CONDITIONING AMPLIFIER C --> PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE A --> REPLACE PRESSURE SENSOR

The solar sensor, which is installed on the upper side of the instrument panel, detects sunlight and controls the air conditioning in AUTO mode. The output voltage from the solar sensor varies according to the amount of sunlight. When the sunlight increases, the output voltage increases. As the sunlight decreases, the output voltage decreases. The A/C amplifier detects output voltage from the solar sensor.

Scheme 28

The air mix damper servo sends pulse signals to inform the air conditioner amplifier of the damper position. The air conditioner amplifier activates the motor (normal, reverse) based on the signals to move the air mix damper (passenger seat) to any position, which adjusts the amount of air passing the heater core after passing the evaporator to control the blowing temperature.

HINT

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

Scheme 29

The damper servo (air inlet control) sends pulse signals to inform the air conditioner amplifier of the damper position. The air conditioner amplifier activates the motor (normal, reverse) based on the 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).

HINT

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

Scheme 30

The mode damper servo sends pulse signals to inform the air conditioner amplifier of the damper position. The air conditioner amplifier activates the motor (normal, reverse) based on the signals to move the mode damper to any position, which controls the air outlet switching.

HINT

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

Scheme 31

The damper servo (cool air by-pass) sends pulse signals to inform the air conditioner amplifier of the damper position. The air conditioner amplifier activates the motor (normal, reverse) based on the signals to move the damper to any position. As a result, when the A/C is operating, the temperature of the air blowing toward the passenger's head area is controlled.

HINT

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

Scheme 32

The air mix damper servo sends pulse signals to inform the air conditioner amplifier of the damper position. The air conditioner amplifier activates the motor (normal, reverse) based on the signals to move the air mix damper (driver seat) 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.

HINT

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

Scheme 33

In this circuit, the compressor receives a refrigerant compression demand signal from the air conditioning amplifier.

Based on this signal, the compressor changes the amount of compressor output.

Scheme 34

The smog ventilation sensor detects NOx in the emission gas and transmits signals to the A/C amplifier. Based on the signals, the A/C amplifier performs automatic air inlet control (FRESH, FRESH / RECIRCULATION, or RECIRCULATION mode).

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

Scheme 35

The A/C amplifier sends a magnetic clutch ON command signal to the ECM through the BEAN line and CAN line. Then the ECM turns the A/C COMP relay on to turn the magnetic clutch on.

Scheme 36

The GLW RLY turns on when it receives a signal from the A/C amplifier. As a result, power is supplied to the heater glow plug.

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1. INSPECT FUSE (LH-IG, GLW PLG1, GLW PLG2) Remove the LH-IG fuse from the cowl side J/B LH. Remove the GLW PLG1 and GLW PLG2 fuses from the engine room R/B and J/B No. 1. Measure the resistance according to the value(s) in the table below. Standard resistance Tester Item Condition Specified Condition LH-IG fuse Always Below 1 ohms GLW PLG1 fuse Always Below 1 ohms GLW PLG2 fuse Always Below 1 ohms NG --> REPLACE FUSE OK: Go to next step
2. INSPECT RELAY (GLW RLY1, GLW RLY2) Remove the GLW RLY1 and GLW RLY2 relays from the engine room R/B and J/B No. 1. Measure the resistance according to the value(s) in the table below. Standard resistance Tester Connection Condition Specified Condition 3 - 5 Always 10 kohms or higher 3 - 5 When battery voltage is applied to terminals 1 and 2 Below 1 ohms NG --> REPLACE RELAY OK: Go to next step
3. CHECK HARNESS AND CONNECTOR (A/C AMPLIFIER - BATTERY) Disconnect the connector from the A/C amplifier. Turn the engine switch on (IG). Measure the voltage according to the value(s) in the table below. Standard voltage Tester Connection (Symbols) Condition Specified Condition J58-4 (HTR2) - Body ground Engine switch on (IG) 10 to 14 V J58-23 (HTR1) - Body ground Engine switch on (IG) 10 to 14 V NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
4. INSPECT AIR CONDITIONING AMPLIFIER Reconnect the connector to the A/C amplifier. Measure the voltage according to the value(s) in the table below. Standard voltage Tester Connection Condition Specified Condition J58-4 (HTR2) - Body ground Engine switch on (IG) 10 to 14 V J58-4 (HTR2) - Body ground Engine switch on (IG) While the PTC operating conditions are met (engine is running at 850 rpm or more, ambient temperature is 0°C (32°F) or less, engine coolant temperature is 69°C (156°F) or less, and A/C switch setting is MAX HOT), turn the blower switch to the LO setting. Below 1 V J58-23 (HTR1) - Body ground Engine switch on (IG) 10 to 14 V J58-23 (HTR1) - Body ground Engine switch on (IG) While the PTC operating conditions are met (engine is running at 850 rpm or more, ambient temperature is 0°C (32°F) or less, engine coolant temperature is 69°C (156°F) or less, and A/C switch setting is MAX HOT), turn the blower switch to the LO setting. Below 1 V NG --> REPLACE AIR CONDITIONING AMPLIFIER OK: Go to next step
5. INSPECT HEATER BLOWER WIRE Remove the grommets and nuts of the water by-pass glow plugs. Turn the engine switch on (IG). Perform Active Test by referring to the table below. ACTIVE TEST / AIR CONDITIONER: Tester Display Test Part Control Range Diagnostic Note Electric Heater1 (Heater1) Electric Heater 1 OFF, ON - Electric Heater2 (Heater2) Electric Heater 2 OFF, ON - Measure the voltage according to the value(s) in the table below. Standard voltage Tester connection Condition Specified condition 1 - Body ground Perform ACTIVE TEST / HEATER 1 (Electric Heater 1): ON 10 to 14 V 2 - Body ground Perform ACTIVE TEST / HEATER 2 (Electric Heater 2): ON 10 to 14 V NG --> REPAIR OR REPLACE HEATER BLOWER WIRE OK: Go to next step
6. INSPECT WATER BY-PASS GLOW PLUG Remove the water by-pass glow plug. Measure the resistance according to the value(s) in the table below. Standard resistance Below 1 ohms NG --> REPLACE WATER BY-PASS GLOW PLUG OK --> PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE

The main power source is supplied to the A/C amplifier when the engine switch on (IG).

The power source is used for operating the A/C amplifier and servo motor, etc.

Scheme 39

The back-up power source circuit for the A/C amplifier is shown below. Power is supplied even when turning the engine switch off and is used for diagnostic trouble code memory, etc.

Scheme 40

See also:
• ON-VEHICLE INSPECTION [08/2012 - ]