AIR CONDITIONING SYSTEM (for Manual Air Conditioning System), Diagnostic DTC:B1413

DESCRIPTION

The No. 1 cooler thermistor (evaporator temperature sensor) is installed on the evaporator in the air conditioning unit to detect the temperature of the cooled air 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 temperature of the cooled air 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.

INSPECTION PROCEDURE

PROCEDURE

1. Click here

   READ VALUE USING INTELLIGENT TESTER

   
   

   1. Use the Data List to check if the No. 1 cooler thermistor is functioning properly.

      Table 1. Air Conditioner

      Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
      Evaporator Fin Thermistor	No. 1 cooler thermistor / Min.: -29.7°C (-21.46°F) Max.: 59.55°C (139.19°F)	Actual evaporator temperature displayed	Open in the circuit: -29.7°C (-21.46°F). Short in the circuit: 59.55°C (139.19°F).
      Evaporator Target Temp	Target evaporator temperature / Min.: -327.68°C (-557.82°F) Max.: 327.67°C (621.81°F)	Target evaporator temperature displayed	-

      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 NO. 1 COOLER THERMISTOR

   
   
   1. 

      Remove the No. 1 cooler 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 (14°F) 7.30 to 9.10 kΩ -5°C (23°F) 5.65 to 6.95 kΩ 0°C (32°F) 4.40 to 5.35 kΩ 5°C (41°F) 3.40 to 4.15 kΩ 10°C (50°F) 2.70 to 3.25 kΩ 15°C (59°F) 2.14 to 2.58 kΩ 20°C (68°F) 1.71 to 2.05 kΩ 25°C (77°F) 1.38 to 1.64 kΩ 30°C (86°F) 1.11 to 1.32 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).

      Table 3. Result

      Result	Proceed to
      OK (except 1WW Engine)	A
      OK (for 1WW Engine)	B
      NG	C

   
   
   • AClick here
   • BClick here
   • CClick here
3. Click here

   CHECK HARNESS AND CONNECTOR (NO. 1 COOLER THERMISTOR - AIR CONDITIONING AMPLIFIER)

   
   
   1. 

      Disconnect the H45 thermistor connector.

   2. Disconnect the H9 amplifier connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition H9-10 (TE) - H45-1 Always Below 1 Ω H9-11 (SG-3) - H45-2 Always Below 1 Ω H9-10 (TE) - Body ground Always 10 kΩ or higher H9-11 (SG-3) - Body ground Always 10 kΩ or higher

      Table 4. Text in Illustration

      *1	Front view of wire harness connector (to No. 1 Cooler Thermistor)
      *2	Front view of wire harness connector (to Air Conditioning Amplifier Assembly)

   
   
   • OKClick here
   • NGClick here
4. Click here

   CHECK HARNESS AND CONNECTOR (NO. 1 COOLER THERMISTOR - AIR CONDITIONING AMPLIFIER)

   
   
   1. 

      Disconnect the H45 thermistor connector.

   2. Disconnect the H118 amplifier connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition H118-4 (TE) - H45-1 Always Below 1 Ω H118-15 (SG-3) - H45-2 Always Below 1 Ω H118-4 (TE) - Body ground Always 10 kΩ or higher H118-15 (SG-3) - Body ground Always 10 kΩ or higher

      Table 5. Text in Illustration

      *1	Front view of wire harness connector (to No. 1 Cooler Thermistor)
      *2	Front view of wire harness connector (to Air Conditioning Amplifier Assembly)

   
   
   • OKClick here
   • NGClick here
5. Click here

   REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLYClick here

6. Click here

   REPLACE NO. 1 COOLER THERMISTORClick here

7. Click here

   REPAIR OR REPLACE HARNESS OR CONNECTOR

8. Click here

   PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLEClick here