Toyota Tundra Service Manual: Evaporator Temperature Sensor Circuit (B1413/13)

DESCRIPTION

The No. 1 cooler thermistor is installed on the evaporator in the air conditioner unit to detect the cooled air temperature that has passed through the evaporator and control the air conditioning. It sends appropriate signals to the air conditioning amplifier. The resistance of the No. 1 cooler thermistor changes in accordance with the cooled air temperature that has passed through the evaporator. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.

The air conditioning amplifier 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.

DTC Code

DTC Detection Condition

Trouble Area

B1413/13

Open or short in evaporator temperature sensor circuit

  • No. 1 cooler thermistor
  • Air conditioning harness
  • Air conditioning amplifier

WIRING DIAGRAM

PROCEDURE

1.

READ VALUE USING TECHSTREAM (EVAPORATOR FIN THERMISTOR)

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

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 No. 1 cooler thermistor 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.

Result

Result

Proceed to

NG

A

OK (Checking from the PROBLEM SYMPTOMS TABLE)

B

OK (Checking from the DTC)

C

B

PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE

C

REPLACE AIR CONDITIONING AMPLIFIER

A

2.

INSPECT NO. 1 COOLER THERMISTOR

(a) Remove the No. 1 cooler thermistor connector (see page ).

(b) 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

NOTICE:

  • 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.

HINT:

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

NG

REPLACE NO. 1 COOLER THERMISTOR

OK

3.

REPAIR OR REPLACE AIR CONDITIONING HARNESS

(a) Repair or replace the air conditioning harness.

NEXT

4.

CHECK FOR DTC

(a) Clear the DTC (see page ).

(b) Check for DTC (see page ).

OK:

DTC is not output.

OK

END (AIR CONDITIONING HARNESS IS DEFECTIVE)

NG

REPLACE AIR CONDITIONING AMPLIFIER

    Ambient Temperature Sensor Circuit (B1412/12)

    Solar Sensor Circuit (Passenger Side) (B1421/21)

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