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Air Conditioning System (Diagnostic Codes & Circuit Tests): Overview Lexus GS IV

Automatic HVAC System 29 illustrations ~2794 words

DESCRIPTION

The cooler thermistor is installed in the instrument panel to detect the cabin temperature which is used to control the heater and air conditioning system AUTO mode. The resistance of the 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 cooler thermistor and reads voltage changes due to changes in the resistance of the cooler thermistor.

DTC CodeDTC Detection ConditionTrouble Area
B1411/11Open or short in cooler thermistor circuitCooler thermistor Harness or connector Air conditioning amplifier assembly

Scheme 210

Scheme 210: WIRING DIAGRAM

The 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 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 thermistor assembly and reads voltage changes due to changes in the resistance of the thermistor assembly.

DTC CodeDTC Detection ConditionTrouble Area
B1412/12Open or short in thermistor assembly circuitThermistor assembly Harness or connector Air conditioning amplifier assembly

Scheme 211

Scheme 211: WIRING DIAGRAM

The No. 1 cooler thermistor is installed on the evaporator in the air conditioner unit to detect the temperature of the 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 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.

DTC CodeDTC Detection ConditionTrouble Area
B1413/13Open or short in No. 1 cooler thermistor circuitNo. 1 cooler thermistor Air conditioning harness assembly Air conditioning amplifier assembly

Scheme 212

Scheme 212: WIRING DIAGRAM

The smog ventilation sensor is installed to the front of the cooler condenser assembly and is used to control automatic switching between recirculation and fresh air modes. The smog ventilation sensor detects components of the exhaust gas (CO, HC) and transmits a signal to the air conditioning amplifier assembly.

DTC CodeDTC Detection ConditionTrouble Area
B1418/18Short in smog ventilation sensor circuit (HC, CO)Smog ventilation sensor Harness or connector Air conditioning amplifier assembly

Scheme 213

Scheme 213: WIRING DIAGRAM

This DTC is stored if refrigerant pressure on the high pressure side is extremely low (196 kPa [2.0 kgf/cm 2 , 28 psi] or less) or extremely high (3138 kPa [32 kgf/cm 2 , 455 psi] or more). The air conditioner 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.

DTC CodeDTC Detection ConditionTrouble Area
B1423/23Open or short in air conditioner pressure sensor circuit Refrigerant pressure on the high pressure side is extremely low (196 kPa [2.0 kgf/cm 2 , 28 psi) or less] or extremely high (3138 kPa [32 kgf/cm 2 , 455 psi] or more).Air conditioner pressure sensor Harness or connector Air conditioning amplifier assembly Cooler expansion valve (blocked, stuck) Cooler dryer (moisture in the refrigerant cycle cannot be absorbed) Cooler condenser assembly (blocked, deterioration of cooling capacity due to dirt) Cooling fan system (condenser assembly cannot be cooled down) Refrigerant

Scheme 214

Scheme 214: WIRING DIAGRAM

The No. 2 air conditioning radiator damper servo sub-assembly (front passenger side upper air mix) 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. 2 air conditioning radiator damper servo sub-assembly (front passenger side upper air mix) 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.

DTC CodeDTC Detection ConditionTrouble Area
B1441/41Air mix damper position sensor value does not change even if air conditioning amplifier assembly operates No. 2 air conditioning radiator damper servo sub-assembly (front passenger side upper air mix)No. 2 air conditioning radiator damper servo sub-assembly (front passenger side upper air mix) Air conditioning harness assembly Air conditioning amplifier assembly

Scheme 215

Scheme 215: WIRING DIAGRAM

The No. 1 blower damper servo sub-assembly 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 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 assembly.

DTC CodeDTC Detection ConditionTrouble Area
B1442/42Air inlet damper position sensor value does not change even if air conditioning amplifier assembly operates No. 1 blower damper servo sub-assemblyNo. 1 blower damper servo sub-assembly Air conditioning harness assembly Air conditioning amplifier assembly

Scheme 216

Scheme 216: WIRING DIAGRAM

The No. 6 air conditioning radiator damper servo sub-assembly 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. 6 air conditioning radiator damper servo sub-assembly 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.

DTC CodeDTC Detection ConditionTrouble Area
B1443/43Air outlet damper position sensor value does not change even if air conditioning amplifier assembly operates No. 6 air conditioning radiator damper servo sub-assemblyNo. 6 air conditioning radiator damper servo sub-assembly Air conditioning harness assembly Air conditioning amplifier assembly

Scheme 217

Scheme 217: WIRING DIAGRAM

The No. 2 air conditioning radiator damper servo sub-assembly (driver side upper air mix) 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 No. 2 air conditioning radiator damper servo sub-assembly (driver side upper air mix) 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.

DTC CodeDTC Detection ConditionTrouble Area
B1446/46Air mix damper position sensor value does not change even if air conditioning amplifier assembly operates No. 2 air conditioning radiator damper servo sub-assembly (driver side upper air mix)No. 2 air conditioning radiator damper servo sub-assembly (driver side upper air mix) Air conditioning harness assembly Air conditioning amplifier assembly

Scheme 218

Scheme 218: WIRING DIAGRAM

The No. 3 air conditioning damper servo sub-assembly (rear side air mix) 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. 3 air conditioning damper servo sub-assembly (rear side air mix) 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.

DTC CodeDTC Detection ConditionTrouble Area
B1447/47Air mix damper position sensor value does not change even if air conditioning amplifier assembly operates No. 3 air conditioning damper servo sub-assembly (rear side air mix)No. 3 air conditioning damper servo sub-assembly (rear side air mix) Air conditioning harness assembly Air conditioning amplifier assembly

Scheme 219

Scheme 219: WIRING DIAGRAM

The No. 5 air conditioning radiator damper servo sub-assembly 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. 5 air conditioning radiator damper servo sub-assembly 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.

DTC CodeDTC Detection ConditionTrouble Area
B1448/48Front passenger side air mix damper position does not change even if air conditioning amplifier assembly operates No. 5 air conditioning radiator damper servo sub-assemblyNo. 5 air conditioning radiator damper servo sub-assembly Air conditioning harness assembly Air conditioning amplifier assembly

Scheme 220

Scheme 220: WIRING DIAGRAM

The No. 7 air conditioning radiator damper servo sub-assembly 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. 7 air conditioning radiator damper servo sub-assembly 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.

DTC CodeDTC Detection ConditionTrouble Area
B1449/49Air outlet damper position sensor value does not change even if air conditioning amplifier assembly operates No. 7 air conditioning radiator damper servo sub-assemblyNo. 7 air conditioning radiator damper servo sub-assembly Air conditioning harness assembly Air conditioning amplifier assembly

Scheme 221

Scheme 221: WIRING DIAGRAM

The No. 4 air conditioning radiator damper servo sub-assembly (driver side lower air mix) 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 No. 4 air conditioning radiator damper servo sub-assembly (driver side lower air mix) 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 lower 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.

DTC CodeDTC Detection ConditionTrouble Area
B1453/53Air mix damper position sensor value does not change even if air conditioning amplifier assembly operates No. 4 air conditioning radiator damper servo sub-assembly (driver side lower air mix)No. 4 air conditioning radiator damper servo sub-assembly (driver side lower air mix) Air conditioning harness assembly Air conditioning amplifier assembly

Scheme 222

Scheme 222: WIRING DIAGRAM

The No. 3 air conditioning radiator damper servo sub-assembly (front passenger side lower air mix) 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. 3 air conditioning radiator damper servo sub-assembly (front passenger side lower air mix) 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 front passenger side lower 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.

DTC CodeDTC Detection ConditionTrouble Area
B1454/54Air mix damper position does not change even if air conditioning amplifier assembly operates No. 3 air conditioning radiator damper servo sub-assembly (front passenger side lower air mix)No. 3 air conditioning radiator damper servo sub-assembly (front passenger side lower air mix) Air conditioning harness assembly Air conditioning amplifier assembly

Scheme 223

Scheme 223: WIRING DIAGRAM

The No. 1 air conditioning radiator damper servo sub-assembly 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 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.

DTC CodeDTC Detection ConditionTrouble Area
B1455/55Air outlet damper position sensor value does not change even if air conditioning amplifier assembly operates No. 1 air conditioning radiator damper servo sub-assemblyNo. 1 air conditioning radiator damper servo sub-assembly Air conditioning harness assembly Air conditioning amplifier assembly

Scheme 224

Scheme 224: WIRING DIAGRAM

The smog ventilation sensor is installed to the front of the cooler condenser assembly and is used to control automatic switching between recirculation and fresh air modes. The smog ventilation sensor detects components of the exhaust gas (NOx) and transmits a signal to the air conditioning amplifier assembly.

DTC CodeDTC Detection ConditionTrouble Area
B1461/61Short in smog ventilation sensor circuit (NOx)Smog ventilation sensor Harness or connector Air conditioning amplifier assembly

Scheme 225

Scheme 225: WIRING DIAGRAM

The compressor with motor assembly monitors the voltage of the HV battery. It stops compressor control and stores the DTC when the monitored voltage is outside the specified range.

The DTC will be stored as a history DTC. Compressor control may not resume unless the power switch is turned off.

DTC CodeDTC Detection ConditionTrouble Area
B1471/71Open or short in compressor with motor assembly high voltage power resource system. The boost inverter is broken or malfunctioning.CAN communication system Hybrid control system High voltage fuse Air conditioning harness Compressor with motor assembly

Scheme 226

Scheme 226: WIRING DIAGRAM

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 store the DTC. The DTC will be stored as a history DTC. The compressor operation remains stopped until both the history and current DTCs are cleared.

DTC CodeDTC Detection ConditionTrouble Area
B1472/72Open or short in compressor with motor assembly high voltage output system.Compressor with motor assembly CAN communication system

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.

DTC CodeDTC Detection ConditionTrouble Area
B1473/73Open or short in compressor with motor assembly start-up signal system.CAN communication system Hybrid control system Harness or connector Compressor with motor assembly Power management control ECU
DTC CodeDTC Detection ConditionTrouble Area
B1474/74Compressor with motor assembly malfunctionCompressor with motor assembly CAN communication system

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

If the temperature exceeds the maximum, the operation of the compressor with motor assembly will be stopped, and DTC B1475/75 will be stored.

DTC CodeDTC Detection ConditionTrouble Area
B1475/75Temperature of the inverter is outside the specified range (temperature is too high), or there is an open or short to ground in the temperature sensor circuit.Cooling fan system Refrigerant volume Compressor with motor assembly CAN communication system

The operation of the compressor with motor assembly is stopped and a DTC B1476/76 is stored if the rotation load is too large or too small while the compressor with motor assembly is operating.

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

DTC CodeDTC Detection ConditionTrouble Area
B1476/76Motor rotation load while the compressor is operating is too large or too small.Cooling fan system Refrigerant volume Compressor with motor assembly CAN communication system

The compressor with motor assembly monitors the control power voltage in the circuit. It stops the compressor circuit and stores the DTC B1477/77 when the monitored voltage is outside the specified range.

This DTC will be stored as a history DTC. Compressor control may not resume unless the power switch is turned off.

DTC CodeDTC Detection ConditionTrouble Area
B1477/77An open or short to ground in the inverter control power voltage circuit.Compressor with motor assembly CAN communication system

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.

DTC CodeDTC Detection ConditionTrouble Area
B1497/97Error or open in communication lineAir conditioning harness assembly No. 1 air conditioning radiator damper servo sub-assembly No. 2 air conditioning radiator damper servo sub-assembly (driver side upper air mix) No. 2 air conditioning radiator damper servo sub-assembly (front passenger side upper air mix) No. 3 air conditioning radiator damper servo sub-assembly (front passenger side lower air mix) No. 4 air conditioning radiator damper servo sub-assembly (driver side lower air mix) No. 5 air conditioning radiator damper servo sub-assembly No. 6 air conditioning radiator damper servo sub-assembly No. 7 air conditioning radiator damper servo sub-assembly No. 1 blower damper servo sub-assembly No. 3 air conditioning radiator damper servo sub-assembly (rear air mix) Air conditioning amplifier assembly

Scheme 227

Scheme 227: WIRING DIAGRAM

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 stored if communication information is cut off or abnormal information occurs.

The DTC B1498/98 is also detected if high voltage power supplied from the inverter with converter assembly to the compressor control circuit is shut off.

This DTC will be stored as a history DTC.

DTC CodeDTC Detection ConditionTrouble Area
B1498/98Communication line error or open between the power management control ECU and compressor with motor assembly. High voltage power source is shut off.CAN communication system Hybrid control system High voltage fuse Air conditioning harness Harness or connector Compressor with motor assembly Power management control ECU

The 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 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 automatic light control sensor.

DTC CodeDTC Detection ConditionTrouble Area
B14A3Short in passenger side automatic light control sensor circuitAutomatic light control sensor Harness or connector Main body ECU (multiplex network body ECU) Air conditioning amplifier assembly

Scheme 228

Scheme 228: WIRING DIAGRAM

The air conditioner thermistor assembly is installed to the glass window and detects the temperature of the glass window for use in the heater and air conditioner "AUTO" operation. The resistance of the air conditioner thermistor assembly changes according to changes in the temperature of the glass window. When the temperature of the glass window decreases, the resistance increases, and when the temperature of the glass window increases, the resistance decreases. The air conditioning amplifier assembly supplies voltage (5 V) to the air conditioner thermistor assembly and monitors the changes in voltage that result from the changes in the resistance of the air conditioner thermistor assembly.

The glass temperature sensor is integrated with the air conditioning thermistor assembly.

DTC CodeDTC Detection ConditionTrouble Area
B14A8Open or short in glass temperature sensor circuitAir conditioning thermistor assembly Harness or connector Air conditioning amplifier assembly

Scheme 229

Scheme 229: WIRING DIAGRAM

The air conditioner thermistor assembly is installed to the glass window and detects the temperature near the glass window for use in the heater and air conditioner "AUTO" operation. The resistance of the air conditioner thermistor assembly changes according to changes in the temperature near the glass window. When the temperature near the glass window decreases, the resistance increases, and when the temperature near the glass window increases, the resistance decreases. The air conditioning amplifier assembly supplies voltage (5 V) to the air conditioner thermistor assembly and monitors the changes in voltage that result from the changes in the resistance of the air conditioner thermistor assembly.

The glass surroundings temperature sensor is integrated with the air conditioning thermistor assembly.

DTC CodeDTC Detection ConditionTrouble Area
B14A9Open or short in air conditioner thermistor assembly circuitAir conditioning thermistor assembly Harness or connector Air conditioning amplifier assembly

Scheme 230

Scheme 230: WIRING DIAGRAM

The air conditioner thermistor assembly is installed to the glass window and detects the humidity in the cabin for use in the heater and air conditioner "AUTO" operation. The voltage of the air conditioner thermistor assembly changes according to changes in the humidity in the cabin. The air conditioning amplifier assembly monitors changes in the voltage.

The glass humidity sensor is integrated with the air conditioning thermistor assembly.

DTC CodeDTC Detection ConditionTrouble Area
B14AAOpen or short in glass humidity sensor circuitAir conditioning thermistor assembly Harness or connector Air conditioning amplifier assembly

Scheme 231

Scheme 231: WIRING DIAGRAM

The rear control switch communicates with 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 rear control switch is operated.

DTC CodeDTC Detection ConditionTrouble Area
B14B3Lost communication with the rear control switch.Rear control switch Air conditioning amplifier assembly LIN communication system Harness or connector

Scheme 232

Scheme 232: WIRING DIAGRAM

SYSTEM DESCRIPTION

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.

DTC CodeDTC Detection ConditionTrouble Area
B14B8When the following condition is detected using the refrigerant shortage check in normal operation: The amount of refrigerant is insufficient.Refrigerant Refrigerant pipe line Cooler expansion valve Air conditioning amplifier assembly

The DTC is stored if there is insulation trouble with the high voltage circuit 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.

A high voltage motor 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 (ND-OIL 8) is used.

DTC CodeDTC Detection ConditionTrouble Area
P0AA6-611High voltage system insulation malfunctionRefrigerant pipe line Compressor with motor assembly CAN communication system
DTC CodeDTC Detection ConditionTrouble Area
U0131No communication with power steering ECU assemblyCAN communication system Power steering ECU assembly Air conditioning amplifier assembly
U0142No communication with main body ECU (multiplex network body ECU)CAN communication system Main body ECU (multiplex network body ECU) Air conditioning amplifier assembly
U0155No communication with combination meter assemblyCAN communication system Combination meter assembly Air conditioning amplifier assembly
U0163No communication with multi-media module receiver assemblyCAN communication system Multi-media module receiver assembly Air conditioning amplifier assembly
U0293No communication with power management control ECUCAN communication system Power management control ECU Air conditioning amplifier assembly

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

Scheme 233

Scheme 233: WIRING DIAGRAM

The heater accessory 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 hybrid vehicle control ECU operates the water pump relay and drives the heater accessory assembly.

Scheme 234

Scheme 234: WIRING DIAGRAM

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

Control ECUCondition
Air Conditioning Amplifier AssemblyBlower switch: Lo
Temperature set to HI
ECO drive mode off
Engine coolant temperature 64°C (147.2°F) or lower
Ambient temperature 10°C (50.0°F) or lower
IDH signal terminal: Below 1 V

QUICK HEATER ASSEMBLY OPERATION CONDITION

HINT

  1. When all operation conditions are met, 2 quick heater assemblies are operated.
  2. The number of quick heater assemblies operated changes according to the engine coolant temperature.

Scheme 235

Scheme 235: WIRING DIAGRAM

When the combination switch is turned to ECO position, the air conditioning amplifier assembly controls the air conditioning system to enhance fuel efficiency.

Scheme 236

Scheme 236: WIRING DIAGRAM

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

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

Scheme 237

Scheme 237: WIRING DIAGRAM

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

Scheme 238

Scheme 238: WIRING DIAGRAM