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

DESCRIPTION

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

INSPECTION PROCEDURE

PROCEDURE

1. Click here

   READ VALUE USING INTELLIGENT TESTER

   
   

   1. Use the Data List to check if the cooler thermistor (room temperature sensor) is functioning properly.

      Table 1. Air Conditioner

      Tester Display	Measurement Item/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 for front 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 column.

      Table 2. Result

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

   
   
   • AClick here
   • BClick here
   • CClick here
2. Click here

   INSPECT COOLER THERMISTOR (ROOM TEMPERATURE SENSOR)

   
   
   1. 

      Remove the room temperature sensor (Click here).

   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.

      Tip:

      As the temperature increases, the resistance decreases (refer to the graph).

   
   
   • OKClick here
   • NGClick here
3. Click here

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

   
   
   1. 

      Disconnect the H38 sensor connector.

   2. Disconnect the H46 amplifier connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition H38-1 - H46-29 (TR) Always Below 1 Ω H38-2 - H46-34 (SG-1) H46-29 (TR) - Body ground Always 10 kΩ or higher H46-34 (SG-1) - Body ground

      Table 3. Text in Illustration

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

   
   
   • OKClick here
   • NGClick here
4. Click here

   REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLYClick here

5. Click here

   REPLACE COOLER THERMISTOR (ROOM TEMPERATURE SENSOR)Click here

6. Click here

   REPAIR OR REPLACE HARNESS OR CONNECTOR

7. Click here

   PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLEClick here