Air Conditioning System (Diagnostic Codes & Circuit Tests): Overview Lexus LX J200 рестайлинг

Scheme 243

Scheme 244

1. ACTUATOR CHECK Start the engine and warm it up. Perform the indicator check. Refer to «CHECK MODE PROCEDURE [01/2012 - ]». Press the "Recirculation/Fresh" switch. By performing the actuator check, each damper, motor, and relay are automatically operated at 1 second intervals in a continuous cycle from step No. 1 to No. 10. During this operation, check the temperature and airflow indicated on the display as well as by hand. TEXT IN ILLUSTRATION *1 Code Display HINT: If a slower display is desired, press the driver temperature up switch to stop the automatic display. The display changes to step operation display mode which allows the display to be changed 1 step for each press of the switch. The buzzer sounds when the display code changes. Codes are displayed from smaller to larger numbers in order. To cancel the check mode, press the OFF switch. FRONT AIR CONDITIONING UNIT Step No. Display Code Conditions Blower Level Air Mix Damper Dr. Pa. Air Mix Damper FrRr Dr. Pa. Airflow Vent Dr. Pa. Airflow Vent FrRr Air Inlet Cool Air Bypass Damper Compressor 1 0 0 0% 0% FACE FACE FRESH -14% OFF 2 1 1 3 2 17 RECIRCULATION/FRESH ON 4 3 17 RECIRCULATION 113.0% 5 4 17 50% 50% B/L B/L 6 5 17 7 6 17 FOOT FOOT FRESH 8 7 17 100% 100% FOOT 9 8 17 F/D 10 9 31 DEF 113.5% REAR AIR CONDITIONING UNIT Step No. Display Code Conditions Rear Blower Level Rear Air Mix Damper Dr. Pa. Rear Airflow Vent Dr. Pa. Rear Magnetic Valve 1 0 0 0% FACE OFF 2 1 3 3 2 17 ON 4 3 17 5 4 17 50% B/L OFF 6 5 17 7 6 17 FOOT 8 7 17 100% 9 8 17 10 9 31

DESCRIPTION

The front room temperature sensor for the front seat is installed in the instrument panel to detect the room temperature and control the heater and air conditioner auto mode. The resistance of the room temperature sensor changes in accordance with the front room 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 front room temperature sensor and reads voltage changes as the resistance of the front room temperature sensor changes. This sensor also sends the appropriate signals to the air conditioning amplifier assembly.

Scheme 245

The ambient temperature sensor is installed in the front part of the condenser to detect the ambient temperature and control the air conditioner auto mode. The sensor connected to the air conditioning amplifier assembly detects fluctuations in the ambient temperature. This data is used for controlling the room 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 246

The No. 1 cooler thermistor is installed on the evaporator in the air conditioner unit to detect the cooled air temperature that has passed through the evaporator and control the air conditioning. It sends appropriate signals to the air conditioning amplifier assembly. The resistance of the No. 1 cooler thermistor 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 No. 1 cooler thermistor and reads voltage changes as the resistance of the No. 1 cooler thermistor changes. This sensor is used for frost prevention.

Scheme 247

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

Scheme 248

Scheme 249

1. READ VALUE USING TECHSTREAM (REAR EVAPORATOR TEMPERATURE SENSOR) Use the Data List to check if the rear evaporator temperature sensor is functioning properly. Refer to «DATA LIST / ACTIVE TEST [01/2012 - ]». AIR CONDITIONER Tester Display Measurement Item/Range Normal Condition Diagnostic Note Ambient Temp Sens (Rear) Rear evaporator temperature sensor / Min.: -29.7°C (-21.46°F) Max.: 59.55°C (139.19°F) Actual rear evaporator temperature displayed Open in the circuit: -29.7°C (-21.46°F). Short in the circuit: 59.55°C (139.19°F). OK The display is as specified in the normal condition. NG --> See step 2 OK --> See step 6
2. INSPECT REAR EVAPORATOR TEMPERATURE SENSOR Remove the No. 2 air conditioning harness assembly. Refer to «DISASSEMBLY [01/2012 - ]». Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 7 (-) - 8 (+) -10°C (14°F) 7.30 to 9.10 kohms -5°C (23°F) 5.65 to 6.95 kohms 0°C (32°F) 4.40 to 5.35 kohms 5°C (41°F) 3.40 to 4.15 kohms 10°C (50°F) 2.70 to 3.25 kohms 15°C (59°F) 2.14 to 2.58 kohms 20°C (68°F) 1.71 to 2.05 kohms 25°C (77°F) 1.38 to 1.64 kohms 30°C (86°F) 1.11 to 1.32 kohms NOTE: Even slightly touching the sensor may change the resistance value. Be sure to hold the connector of the sensor. When measuring, the sensor temperature must be the same as the ambient temperature. HINT: As the temperature increases, the resistance decreases (See the graph in illustration). NG --> See step 7 OK: Go to next step
3. CHECK HARNESS AND CONNECTOR (NO. 2 AIR CONDITIONING HARNESS - AIR CONDITIONING AMPLIFIER) Disconnect the K19 No. 2 air conditioning harness assembly connector. Disconnect the E35 amplifier connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition K19-8 (+) - E35-17 (TEC) Always Below 1 ohms K19-7 (-) - E35-1 (SG) E35-17 (TEC) - Body ground Always 10 kohms or higher E35-1 (SG) - Body ground E35-17 (TEC) - E35-1 (SG) NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
4. CHECK NO. 2 AIR CONDITIONING HARNESS ASSEMBLY (OPERATION) Replace the No. 2 air conditioning harness assembly with a normal one and check that the condition returns to normal. Refer to «DISASSEMBLY [01/2012 - ]». NEXT: Go to next step
5. CHECK FOR DTC Clear the DTCs. Refer to «DTC CHECK / CLEAR [01/2012 - ]». Check for DTCs. Refer to «DTC CHECK / CLEAR [01/2012 - ]». OK DTC B1417/17 is not output. NG --> See step 9 OK --> See step 8
6. REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to «REMOVAL [01/2012 - ]»
7. REPLACE NO. 2 AIR CONDITIONING HARNESS ASSEMBLY. Refer to «DISASSEMBLY [01/2012 - ]»
8. REPLACE NO. 2 AIR CONDITIONING HARNESS ASSEMBLY. Refer to «DISASSEMBLY [01/2012 - ]»
9. REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to «REMOVAL [01/2012 - ]»

The smog ventilation sensor, which is installed on the front of the cooler condenser assembly, automatically changes to fresh, fresh/recirculation or recirculation mode operation. The smog ventilation sensor detects CO and HC in the emission gas and transmits signals to the air conditioning amplifier assembly.

Scheme 250

The rear room temperature sensor LH is installed in the rear quarter trim board LH to detect the rear room temperature and control the heater and air conditioner auto mode. The resistance of the rear room temperature sensor LH changes in accordance with the rear room temperature for the LH seat. 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 rear room temperature sensor LH and reads voltage changes as changes in the resistance of the rear room temperature sensor LH.

Scheme 251

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 magnet clutch off.

Scheme 252

This DTC is stored when refrigerant pressure is extremely low (0.1762 MPa (1.8 kgf/cm 2 , 25 psi) or less) or extremely high (3.0732 MPa (31.4 kgf/cm 2 , 445 psi) or more). The air conditioner pressure sensor, which is installed on the pipe of the high pressure side to detect refrigerant pressure, outputs the refrigerant pressure signal to the air conditioning amplifier assembly. The air conditioning amplifier assembly converts the 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 stored if there is no refrigerant in the cycle.

Scheme 253

The duct sensor RH (for front passenger side) detects the duct temperature and sends the appropriate signals to the air conditioning amplifier assembly.

Scheme 254

Scheme 255

1. READ VALUE USING TECHSTREAM (DUCT SENSOR RH) Use the Data List to check if the duct sensor RH (for front passenger side) is functioning properly. Refer to «DATA LIST / ACTIVE TEST [01/2012 - ]». AIR CONDITIONER Tester Display Measurement Item/Range Normal Condition Diagnostic Note Foot Duct Sensor (Rear P) Duct sensor / Min.: -12.7°C (9.14°F) Max.: 76.55°C (169.79°F) Actual temperature measured by duct sensor RH displayed Open in the circuit: -12.7°C (9.14°F). Short in the circuit: 76.55°C (169.79°F). OK The display is as specified in the normal condition. NG --> See step 2 OK --> See step 4
2. CHECK DUCT SENSOR RH Remove the duct sensor RH. Refer to «REMOVAL [01/2012 - ]». Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 1 - 2 10°C (50°F) 9.4 to 10.5 kohms 15°C (59°F) 7.5 to 8.3 kohms 20°C (68°F) 6.0 to 6.5 kohms 25°C (77°F) 4.8 to 5.2 kohms 30°C (86°F) 3.8 to 4.2 kohms 35°C (95°F) 3.1 to 3.4 kohms 40°C (104°F) 2.5 to 2.8 kohms 45°C (113°F) 2.0 to 2.3 kohms 50°C (122°F) 1.6 to 2.0 kohms 55°C (131°F) 1.3 to 1.6 kohms 60°C (140°F) 1.1 to 1.4 kohms NOTE: Touching the sensor even slightly may change the resistance value. Hold the connector of the sensor. When measuring the resistance, the sensor temperature must be the same as the ambient temperature. HINT: As the temperature increases, the resistance decreases (See the graph in illustration). If the resistance value is not as specified, replace the sensor. NG --> See step 5 OK: Go to next step
3. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - DUCT SENSOR) Disconnect the L11 sensor connector. Disconnect the E35 amplifier connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition E35-26 (TR4) - L11-1 Always Below 1 ohms E35-12 (SG-9) - L11-2 E35-26 (TR4) - Body ground Always 10 kohms or higher E35-12 (SG-9) - Body ground E35-26 (TR4) - E35-12 (SG-9) NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK --> See step 4
4. REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to «REMOVAL [01/2012 - ]»
5. REPLACE DUCT SENSOR RH. Refer to «REMOVAL [01/2012 - ]»

The front air mix damper servo motor (for front passenger side) sends pulse signals to inform the air conditioning amplifier assembly of the damper position. The air conditioning amplifier assembly activates the motor (normal or reverse) based on the signals to move the front air mix damper (for front passenger side) to any position. As a result, the amount of air that has passed through the evaporator and is passing through the heater core is adjusted, and the temperature of the air blowing toward the front passenger side is controlled.

HINT

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

Scheme 256

The REC/FRS damper servo motor sends pulse signals to inform the air conditioning amplifier assembly of the damper position. The air conditioning amplifier assembly activates the motor (normal or reverse) based on the signals to move the air inlet 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 trouble code can be stored when either a damper link or damper is mechanically locked.

Scheme 257

The air outlet damper servo motor (for driver side mode) sends pulse signals to inform the air conditioning amplifier assembly of the damper position. The air conditioning amplifier assembly activates the motor (normal or reverse) based on the signals to move the air outlet damper (for driver side mode) to any position, which controls the air outlet changes.

HINT

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

Scheme 258

The cool air bypass damper servo motor sends pulse signals to inform the air conditioning amplifier assembly of the damper position. The air conditioning amplifier assembly activates the motor (normal or reverse) based on the signals to move the cool air bypass damper to any position. As a result, when the air conditioner is operating, the temperature of the air blowing toward the head area is controlled.

HINT

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

Scheme 259

The front air mix damper servo motor (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 or reverse) based on the signals to move the air mix damper (for driver side) to any position. As a result, the amount of air that has passed through the evaporator and is passing through the heater core is adjusted, and the temperature of the air blowing toward the driver side is controlled.

HINT

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

Scheme 260

The rear air mix damper servo motor LH 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 rear air mix damper 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 blown air.

HINT

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

Scheme 261

The air outlet damper servo motor (for front passenger side mode) sends pulse signals to inform the air conditioning amplifier assembly of the damper position. The air conditioning amplifier assembly activates the motor (normal or reverse) based on the signals to move the air outlet damper (for front passenger side mode) to any position, which controls the air outlet changes.

HINT

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

Scheme 262

The rear air outlet damper servo motor sends pulse signals to inform the air conditioning amplifier assembly of the damper position. The air conditioning amplifier assembly activates the motor (normal or reverse) based on the signals to move the rear air outlet damper to the appropriate position, which controls the air outlet modes.

HINT

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

Scheme 263

The front air mix damper servo motor (for driver side rear air flow) sends pulse signals to inform the air conditioning amplifier assembly of the damper position. The air conditioning amplifier assembly activates the motor (normal or reverse) based on the signals to move the front air mix damper (for driver side rear air flow) to any position. As a result, the amount of air that has passed through the evaporator and is passing through the heater core is adjusted, and the temperature of the air blowing toward the rear driver side is controlled.

HINT

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

Scheme 264

The front air mix damper servo motor (for front passenger side rear air flow) sends pulse signals to inform the air conditioning amplifier assembly of the damper position. The air conditioning amplifier assembly activates the motor (normal or reverse) based on the signals to move the front air mix damper (for front passenger side rear air flow) to any position. As a result, the amount of air that has passed through the evaporator and is passing through the heater core is adjusted, and the temperature of the air blowing toward the rear passenger side is controlled.

HINT

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

Scheme 265

The smog ventilation sensor, which is installed on the front of the cooler condenser assembly, automatically changes to fresh, fresh/recirculation or recirculation mode operation. The smog ventilation sensor detects NOx in the emission gas and transmits signals to the air conditioning amplifier assembly.

The duct sensor LH (for driver side) detects the duct temperature and sends the appropriate signals to the air conditioning amplifier assembly.

Scheme 266

The rear room temperature sensor RH is installed in the rear quarter trim board RH to detect the rear room temperature and control the heater and air conditioner auto mode. The resistance of the rear room temperature sensor RH changes in accordance with the rear room temperature for RH seat. 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 rear room temperature sensor RH and reads voltage changes as changes in the resistance of the rear room temperature sensor RH.

Scheme 267

Scheme 268

1. READ VALUE USING TECHSTREAM (REAR ROOM TEMPERATURE SENSOR RH) Use the Data List to check if the rear room temperature sensor RH is functioning properly. Refer to «DATA LIST / ACTIVE TEST [01/2012 - ]». AIR CONDITIONER Tester Display Measurement Item/Range Normal Condition Diagnostic Note Room Temperature Sensor (RP) Rear room temperature sensor RH / Min.: -6.5°C (20.3°F) Max.: 57.25°C (135.05°F) Actual rear room temperature for RH seat displayed Open in the circuit: -6.5°C (20.3°F). Short in the circuit: 57.25°C (135.05°F). OK The display is as specified in the normal condition. NG --> See step 2 OK --> See step 5
2. INSPECT REAR ROOM TEMPERATURE SENSOR RH Remove the rear room temperature sensor RH. Refer to «REMOVAL [01/2012 - ]». Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 1 - 2 10°C (50°F) 3.00 to 3.73 kohms 15°C (59°F) 2.45 to 2.88 kohms 20°C (68°F) 1.95 to 2.30 kohms 25°C (77°F) 1.60 to 1.80 kohms 30°C (86°F) 1.28 to 1.47 kohms 35°C (95°F) 1.00 to 1.22 kohms 40°C (104°F) 0.80 to 1.00 kohms 45°C (113°F) 0.65 to 0.85 kohms 50°C (122°F) 0.50 to 0.70 kohms 55°C (131°F) 0.44 to 0.60 kohms 60°C (140°F) 0.36 to 0.50 kohms NOTE: Even slightly touching the sensor may change the resistance value. Be sure to hold the connector of the sensor. HINT: As the temperature increases, the resistance decreases (See the graph in illustration). NG --> See step 6 OK: Go to next step
3. CHECK HARNESS AND CONNECTOR (REAR ROOM TEMPERATURE SENSOR RH - AIR CONDITIONING AMPLIFIER) Disconnect the z37 sensor connector. Disconnect the E35 amplifier connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition z37-2 - E35-2 (SG-6) Always Below 1 ohms z37-1 - E35-19 (TR7) E35-19 (TR7) - Body ground Always 10 kohms or higher E35-2 (SG-6) - Body ground E35-19 (TR7) - E35-2 (SG-6) NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK --> See step 4
4. REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to «REMOVAL [01/2012 - ]»
5. REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to «REMOVAL [01/2012 - ]»
6. REPLACE REAR ROOM TEMPERATURE SENSOR RH. Refer to «REMOVAL [01/2012 - ]»

The air outlet damper servo motor (for rear seat mode) sends pulse signals to inform the air conditioning amplifier assembly of the damper position. The air conditioning amplifier assembly activates the motor (normal or reverse) based on the signals to move the air outlet damper to any position, which controls the air outlet changes.

HINT

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

Scheme 269

The rear air mix damper servo motor RH 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 rear air mix damper 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 blown air.

HINT

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

Scheme 270

The air conditioning harness assembly connects the air conditioning amplifier assembly and each servo motor. 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 the damper position information to the air conditioning amplifier assembly.

Scheme 271

Scheme 272

Scheme 273

The automatic light control sensor (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 current from the solar sensor varies according to the amount of sunlight. When the sunlight increases, the output current increases. As the sunlight decreases, the output current decreases. The air conditioning amplifier assembly detects output current from the solar sensor.

HINT

If DTC B1244 is output at the same time, troubleshoot DTC B1244 first.

Scheme 274

The cooler expansion valve (cooler magnetic valve) is controlled by the air conditioning amplifier assembly (for cool box).

Scheme 275

The cool box blower with fan motor sub-assembly is operated by signals from the air conditioning amplifier assembly (for cool box).

Scheme 276

The cooler control switch sub-assembly is the activation switch for the cool box. If the cool box does not activate when the cooler control switch sub-assembly is pushed, there may be a malfunction in the circuit shown below.

Scheme 277

The No. 3 cooler thermistor is installed on the evaporator in the cooling box unit to detect the cooled air temperature that has passed through the evaporator and control the cooling box. It sends appropriate signals to the air conditioning amplifier assembly (for cool box). The resistance of the No. 3 cooler thermistor 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 (for cool box) applies voltage (12 V) to the No. 3 cooler thermistor and reads voltage changes as the resistance of the No. 3 cooler thermistor changes.

Scheme 278

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 MG CLT relay turns on to operate the magnetic clutch.

Scheme 279

Scheme 280

Scheme 281

1. CHECK CAN COMMUNICATION SYSTEM Check for CAN communication system DTCs related to the air conditioning system. Refer to «DTC CHECK / CLEAR [01/2012 - ]». RESULT Result Proceed to CAN DTC is not output A CAN DTC is output B B --> See step 12 A: Go to next step
2. READ VALUE USING TECHSTREAM (A/C SIGNAL) Use the Data List to check if the A/C switch is functioning properly. Refer to «DATA LIST / ACTIVE TEST [01/2012 - ]». ENGINE Tester Display Measurement Item/Range Normal Condition Diagnostic Note A/C Signal A/C switch signal / ON or OFF ON: A/C switch on OFF: A/C switch off - OK The display is as specified in the normal condition. NG --> See step 3 OK --> See step 11
3. INSPECT FUSE (A/C IG) Remove the A/C IG fuse from the cowl side junction block LH. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition A/C IG fuse Always Below 1 ohms NG --> REPLACE FUSE OK: Go to next step
4. INSPECT MAGNET CLUTCH RELAY (MG CLT) Remove the MG CLT relay from the engine room relay block. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 3 - 5 Battery voltage not applied to terminals 1 and 2 10 kohms or higher 3 - 5 Battery voltage applied to terminals 1 and 2 Below 1 ohms NG --> REPLACE MAGNET CLUTCH RELAY OK: Go to next step
5. CHECK HARNESS AND CONNECTOR (ENGINE ROOM RELAY BLOCK - BATTERY) Remove the MG CLT relay from the engine room relay block. Measure the voltage according to the value(s) in the table below. Standard Voltage Tester Connection Switch Condition Specified Condition Relay block MG CLT relay terminal 5 - Body ground Engine switch on (IG) 11 to 14 V Relay block MG CLT relay terminal 1 - Body ground Engine switch on (IG) 11 to 14 V NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
6. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - BATTERY) Disconnect the E36 amplifier connector. Measure the voltage according to the value(s) in the table below. Standard Voltage Tester Connection Switch Condition Specified Condition E36-18 (MGC) - Body ground Engine switch off Below 1 V E36-18 (MGC) - Body ground Engine switch on (IG) 11 to 14 V NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
7. CHECK HARNESS AND CONNECTOR (ENGINE ROOM RELAY BLOCK - COOLER COMPRESSOR ASSEMBLY) Remove the MG CLT relay from the engine room relay block. Disconnect the C37 compressor connector. Measure the voltage according to the value(s) in the table below. Standard Voltage Tester Connection Switch Condition Specified Condition Relay block MG CLT relay terminal 3- C37-3 (MG+) Always Below 1 ohms Relay block MG CLT relay terminal 3 - Body ground Always 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
8. INSPECT COOLER COMPRESSOR ASSEMBLY Disconnect the C37 compressor connector. Disconnect the A magnet clutch assembly connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition C37-3 (MG+) - A-1 Always Below 1 ohms C37-3 (MG+) - Body ground Always 10 kohms or higher NG --> See step 10 OK: Go to next step
9. INSPECT MAGNET CLUTCH ASSEMBLY Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition A-1 - Body ground 20°C (68°F) 3.4 to 3.8 ohms When connector terminal A-1 is connected to the positive (+) battery terminal, check that the following occurs: 1) the operating sound of the magnet clutch assembly can be heard, and 2) the hub and rotor of the magnet clutch assembly lock. NG --> REPLACE MAGNET CLUTCH ASSEMBLY OK --> See step 13
10. REPLACE COOLER COMPRESSOR ASSEMBLY. Refer to «REMOVAL [01/2012 - ]»
11. REPLACE ECM. Refer to «REMOVAL [01/2012 - ]»
12. GO TO CAN COMMUNICATION SYSTEM. Refer to «HOW TO PROCEED WITH TROUBLESHOOTING [01/2012 - ]»
13. REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to «REMOVAL [01/2012 - ]»

This circuit consists of the No. 2 air conditioning control assembly and the air conditioning amplifier assembly. When the No. 2 air conditioning control assembly is operated, signals are transmitted to the air conditioning amplifier assembly through the LIN communication system.

If the LIN communication system malfunctions, the air conditioning amplifier assembly does not operate even if the No. 2 air conditioning control assembly is operated.

Scheme 282

PTC heater relays are closed in accordance with signals from the air conditioning amplifier assembly and power is supplied to the quick heater assembly installed on the radiator heater unit.

Scheme 283

Scheme 284

Scheme 285

Scheme 286

1. INSPECT PTC HEATER RELAY (PTC HTR1) Remove the PTC HTR1 relay from the engine room relay block. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 3 - 5 Battery voltage is not applied between terminals 1 and 2 10 kohms or higher Battery voltage is applied to terminals 1 and 2 Below 1 ohms NG --> REPLACE PTC HEATER RELAY OK: Go to next step
2. INSPECT PTC HEATER RELAY (PTC HTR2) Remove the PTC HTR2 relay from the engine room relay block. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 3 - 5 Battery voltage is not applied between terminals 1 and 2 10 kohms or higher Battery voltage is applied to terminals 1 and 2 Below 1 ohms NG --> REPLACE PTC HEATER RELAY OK: Go to next step
3. INSPECT PTC HEATER RELAY (PTC HTR3) Remove the PTC HTR3 relay from the engine room relay block. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 3 - 5 Battery voltage is not applied between terminals 1 and 2 10 kohms or higher Battery voltage is applied to terminals 1 and 2 Below 1 ohms NG --> REPLACE PTC HEATER RELAY OK: Go to next step
4. CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY Remove the air conditioning amplifier assembly with its connectors still connected. Refer to «REMOVAL [01/2012 - ]». Measure the voltage according to the value(s) in the table below. Standard Voltage Tester Connection Condition Specified Condition E36-27 (PTC1) - Body ground Engine idling Set temperature: Hi Engine coolant temperature: Below 65°C (149°F) Ambient temperature: Below 10°C (50°F) Blower switch: Off --> Lo Below 1V --> 11 to 14 V E36-26 (PTC2) - Body ground E36-35 (PTC3) - Body ground NG --> See step 8 OK: Go to next step
5. CHECK HARNESS AND CONNECTOR (PTC HEATER RELAY - QUICK HEATER) Remove the PTC heater relays from the engine room relay block. Disconnect the E33 quick heater assembly connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition PTC HTR2 terminal 3 - E33-1 (B) Always Below 1 ohms PTC HTR1 terminal 3 - E33-2 (B) PTC HTR3 terminal 3 - E33-3 (B) PTC HTR2 terminal 3 - Body ground Always 10 kohms or higher PTC HTR1 terminal 3 - Body ground PTC HTR3 terminal 3 - Body ground NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
6. INSPECT QUICK HEATER ASSEMBLY Disconnect the E33 and E34 quick heater assembly connectors. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition E33-1 (B) - E34-1 (E) Always Below 1 kohms E33-2 (B) - E34-1 (E) E33-3 (B) - E34-2 (E) NG --> See step 10 OK: Go to next step
7. CHECK HARNESS AND CONNECTOR (QUICK HEATER - BODY GROUND) Disconnect the E34 quick heater assembly connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition E34-1 (E) - Body ground Always Below 1 ohms E34-2 (E) - Body ground NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
8. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - BODY GROUND) Disconnect the E36 amplifier connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition E36-27 (PTC1) - Body ground Always Below 200 ohms E36-26 (PTC2) - Body ground E36-35 (PTC3) - Body ground NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK --> See step 9
9. REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to «REMOVAL [01/2012 - ]»
10. REPLACE QUICK HEATER ASSEMBLY. Refer to «REMOVAL [01/2012 - ]»

Scheme 287

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

Duty Ratio

The duty ratio is the ratio of the rear blower with fan motor sub-assembly OPEN time (T1) to the total of the rear blower with fan motor sub-assembly OPEN and LO time (T2).

The blower motor control controls the rear blower with fan motor sub-assembly speed.

Scheme 288

The rear cooling unit expansion valve is controlled by the air conditioning amplifier assembly.

Scheme 289

The main power source is supplied to the air conditioning amplifier assembly when the engine switch is on (IG). The power source is used for operating the air conditioning amplifier assembly and servo motor, etc.

Scheme 290

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

Scheme 291

See also:
• REMOVAL [01/2012 - ]