Lexus IS250 · Service Manual HEATER & AIR CONDITIONING SYSTEM

B1413/13

Diagnostic trouble codes

DESCRIPTION

The evaporator temperature sensor (A/C thermistor) is installed on the evaporator in the air conditioner unit. It detects the temperature of the cooled air that has passed through the evaporator and its signal is used to control the air conditioning. It sends a signal to the A/C amplifier. The resistance of the evaporator temperature sensor (A/C 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 A/C amplifier applies voltage (5 V) to the evaporator temperature sensor (A/C thermistor) and reads voltage changes as the resistance of the evaporator temperature sensor (A/C thermistor) changes. This sensor is used to prevent the evaporator from freezing.
DTC No.
 DTC Detection Condition
 Trouble Area
B1413/13
 Open or short in evaporator temperature sensor circuit
  1. Air conditioning harness (evaporator temperature sensor)
  2. A/C amplifier

WIRING DIAGRAM

E118397E02

INSPECTION PROCEDURE


1. READ VALUE OF INTELLIGENT TESTER

  1. Connect the intelligent tester to the DLC3.

  1. Turn the engine switch on (IG) and turn the intelligent tester main switch on.

  1. Select the item below in the Data List, and read the display on the intelligent tester.

    Data List / Air Conditioner: 
    Item
    		 Measurement Item / Display
    (Range)
    		 Normal Condition
    		 Diagnostic Note
    Evaporator Temp Sensor
    (Evap Temp)
    		 Evaporator temperature sensor / Min.: -29.7°C (-21.46°F), Max.: 59.55°C (139.19°F)
    		 Actual evaporator temperature is displayed
    		 Open in circuit: -29.7°C (-21.46°F)
    Short in circuit: 59.55°C (139.19°F)

    OK:
    The display is as 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)
    		 C



B
PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE

C
REPLACE AIR CONDITIONING AMPLIFIER
A


2. INSPECT AIR CONDITIONING HARNESS

  1. E118398E02
    Remove the air conditioning harness (evaporator temperature sensor).

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

    Standard resistance:
    Tester Connection
    		 Condition
    		 Specified Condition
    e1-5 - e1-6
    		 -10°C (14°F)
    		 7.30 to 9.10 kΩ
    e1-5 - e1-6
    		 -5°C (23°F)
    		 5.65 to 6.95 kΩ
    e1-5 - e1-6
    		 0°C (32°F)
    		 4.40 to 5.35 kΩ
    e1-5 - e1-6
    		 5°C (41°F)
    		 3.40 to 4.15 kΩ
    e1-5 - e1-6
    		 10°C (50°F)
    		 2.70 to 3.25 kΩ
    e1-5 - e1-6
    		 15°C (59°F)
    		 2.14 to 2.58 kΩ
    e1-5 - e1-6
    		 20°C (68°F)
    		 1.71 to 2.05 kΩ
    e1-5 - e1-6
    		 25°C (77°F)
    		 1.38 to 1.64 kΩ
    e1-5 - e1-6
    		 30°C (86°F)
    		 1.11 to 1.32 kΩ

    NOTICE:
    1. Even slightly touching the sensor may change the resistance value. Be sure to hold the connector of the sensor.
    2. When measuring, the sensor temperature must be the same as the ambient temperature.

    HINT:
    As the temperature increases, the resistance decreases (see the graph).



 NG
REPLACE AIR CONDITIONING HARNESS
OK

REPLACE AIR CONDITIONING AMPLIFIER


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