AIR CONDITIONING SYSTEM (for Automatic Air Conditioning System), Diagnostic DTC:B1411/11

DESCRIPTION

The room temperature sensor (cooler thermistor) 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 (cooler thermistor) changes in accordance with the room temperature. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.

The air conditioning amplifier applies a voltage (5V) to the room temperature sensor (cooler thermistor) and reads voltage changes as the resistance of the room temperature sensor (cooler thermistor) changes. This sensor also sends the appropriate signals to the air conditioning amplifier.

WIRING DIAGRAM

INSPECTION PROCEDURE

PROCEDURE

1. READ VALUE USING INTELLIGENT TESTER (ROOM TEMPERATURE SENSOR)

   
   

   1. Connect the intelligent tester to the DLC3.

   2. Turn the ignition switch to ON.

   3. Turn the intelligent tester on.

   4. Enter the following menus: Body / Air Conditioner / Data List.

   5. According to the display on the intelligent tester, read the Data List.

      Air Conditioner

      Item	Measurement Item/Display (Range)	Normal Condition	Diagnostic Note
      Room Temperature Sensor	Room temperature sensor / Min.: -6.5°C (20.3°F) Max.: 57.25°C (135.05°F)	Actual room temperature is displayed	Open circuit: -6.5°C (20.3°F) Short circuit: 57.25°C (135.05°F)

      OK
      The display is specified in the normal condition column.

      Result

      Result	Proceed to
      NG	A
      OK (When troubleshooting according to the Problem Symptoms Table)	B
      OK (When troubleshooting according to the DTC output)	C

   
   

   B

   PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Click here

   C

   REPLACE AIR CONDITIONING AMPLIFIER Click here

   A

2. INSPECT ROOM TEMPERATURE SENSOR (COOLER THERMISTOR)

   

   
   

   1. Remove the room temperature sensor (cooler thermistor).

   2. 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 kΩ 15°C (59°F) 2.45 to 2.88 kΩ 20°C (68°F) 1.95 to 2.30 kΩ 25°C (77°F) 1.60 to 1.80 kΩ 30°C (86°F) 1.28 to 1.47 kΩ 35°C (95°F) 1.00 to 1.22 kΩ 40°C (104°F) 0.80 to 1.00 kΩ 45°C (113°F) 0.65 to 0.85 kΩ 50°C (122°F) 0.50 to 0.70 kΩ 55°C (131°F) 0.44 to 0.60 kΩ 60°C (140°F) 0.36 to 0.50 kΩ

      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.

      Tech Tips

      As the temperature increases, the resistance decreases (See the graph).

   3. Reinstall the room temperature sensor (cooler thermistor).

   
   

   NG

   REPLACE ROOM TEMPERATURE SENSOR (COOLER THERMISTOR) Click here

   OK

3. CHECK HARNESS AND CONNECTOR (ROOM TEMPERATURE SENSOR - AIR CONDITIONING AMPLIFIER)

   
   
   1. 

      Text in Illustration

      *1	Front view of wire harness connector (to Room Temperature Sensor (Cooler Thermistor))
      *2	Rear view of wire harness connector (to Air Conditioning Amplifier)

      Disconnect the D11 room temperature sensor (cooler thermistor) connector.

   2. Disconnect the D15 air conditioning amplifier connector.

   3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition D11-1 - D15-29 (TR) Always Below 1 Ω D11-2 - D15-34 (SG-1) Always Below 1 Ω D11-1 - Body ground Always 10 kΩ or higher D11-2 - Body ground Always 10 kΩ or higher

   4. Reconnect the room temperature sensor (cooler thermistor) connector.

   5. Reconnect the air conditioning amplifier connector.

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR

   OK

   REPLACE AIR CONDITIONING AMPLIFIER Click here