AIR CONDITIONING SYSTEM, Diagnostic DTC:B1411/11

DESCRIPTION

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

WIRING DIAGRAM

*a	Cooler (Room Temp. Sensor) Thermistor
*b	Air Conditioning Amplifier Assembly

PROCEDURE

1. READ VALUE USING GTS

   
   

   1. Connect the GTS to the DLC3.

   2. Turn the engine switch on (IG).

   3. Turn the GTS on.

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

   5. Read the Data List according to the display on the GTS.

      Air Conditioner

      Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
      Room Temperature Sensor	Cooler thermistor (room temperature sensor) / min.: -6.50°C (20.30°F) max.: 57.25°C (135.05°F)	Actual cabin temperature displayed	-

      OK
      The display is as specified in the Normal Condition column.

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

   
   

   B

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

   C

   REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

   A

2. INSPECT COOLER (ROOM TEMP. SENSOR) THERMISTOR

   
   

   1. 

      

      Remove the cooler (room temp. sensor) thermistor 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 1 (+) - 2 (-) 15°C (59°F) 2.45 to 2.88 kΩ 1 (+) - 2 (-) 20°C (68°F) 1.95 to 2.30 kΩ 1 (+) - 2 (-) 25°C (77°F) 1.60 to 1.80 kΩ 1 (+) - 2 (-) 30°C (86°F) 1.28 to 1.47 kΩ 1 (+) - 2 (-) 35°C (95°F) 1.00 to 1.22 kΩ 1 (+) - 2 (-) 40°C (104°F) 0.80 to 1.00 kΩ 1 (+) - 2 (-) 45°C (113°F) 0.65 to 0.85 kΩ 1 (+) - 2 (-) 50°C (122°F) 0.50 to 0.70 kΩ 1 (+) - 2 (-) 55°C (131°F) 0.44 to 0.60 kΩ 1 (+) - 2 (-) 60°C (140°F) 0.36 to 0.50 kΩ

      Note

      
      

      • Hold the sensor only by its connector. Touching the sensor may change the resistance value.

      • 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).

      Text in Illustration

      *a	Component without harness connected (Cooler (Room Temp. Sensor) Thermistor)
      *b	Sensing Portion
      *c	Resistance (kΩ)
      *d	Allowable Range
      *e	Temperature (°C (°F))

   
   

   NG

   REPLACE COOLER (ROOM TEMP. SENSOR) THERMISTOR Click here

   OK

3. CHECK HARNESS AND CONNECTOR (COOLER (ROOM TEMP. SENSOR) THERMISTOR - AIR CONDITIONING AMPLIFIER ASSEMBLY)

   
   

   1. Disconnect the H54 air conditioning amplifier assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition H43-1 (+) - H54-29 (TR) Always Below 1 Ω H43-2 (-) - H54-34 (SG-1) Always Below 1 Ω H43-1 (+)- Body ground Always 10 kΩ or higher H43-2 (-) - Body ground Always 10 kΩ or higher

   
   

   OK

   REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR