Toyota CH-R Service Manual: Evaporator Temperature Sensor Circuit (B1413)

DESCRIPTION

The No. 1 cooler thermistor (evaporator temperature sensor) is installed to the evaporator in the air conditioner unit to detect the temperature of the cooled air that has passed through the evaporator, which is used to control the air conditioning system. It sends signals to the air conditioning amplifier assembly. The resistance of the No. 1 cooler thermistor (evaporator temperature sensor) 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 (evaporator temperature sensor) and reads voltage changes as the resistance of the No. 1 cooler thermistor (evaporator temperature sensor) changes. This sensor is used for frost prevention.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Memory

B1413

Evaporator Temperature Sensor Circuit

Any of the following conditions is met:

  • Open in No. 1 cooler thermistor (evaporator temperature sensor) circuit
  • Short in No. 1 cooler thermistor (evaporator temperature sensor) circuit
  • No. 1 cooler thermistor (evaporator temperature sensor)
  • Air conditioning harness assembly (heater radiator unit sub- assembly)
  • Air conditioning amplifier assembly

Memorized

(4 seconds or more)*

  • *: The air conditioning amplifier assembly stores this DTC if the malfunction has occurred for the period of time indicated in the brackets.
DTC Detection Conditions
 

Vehicle Condition

Pattern 1

Pattern 2

Diagnosis Condition

Ignition switch ON

Malfunction Status

Open in No. 1 cooler thermistor (evaporator temperature sensor) circuit

-

Short in No. 1 cooler thermistor (evaporator temperature sensor) circuit

-

Detection Time

4 seconds or more

4 seconds or more

Number of Trips

1 trip

1 trip

HINT:

DTC will be output when conditions for either of the patterns in the table above are met.

WIRING DIAGRAM

PROCEDURE

1.

READ VALUE USING TECHSTREAM (EVAPORATOR FIN THERMISTOR)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch ON.

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Air Conditioner / Data List.

(e) Read the Data List according to the display on the Techstream.

Body Electrical > Air Conditioner > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Evaporator Fin Thermistor

No. 1 cooler thermistor (evaporator temperature sensor)

Min.: -29.70°C (-21.46°F)

Max.: 59.55°C (139.19°F)

Actual evaporator temperature displayed

-

Body Electrical > Air Conditioner > Data List

Tester Display

Evaporator Fin Thermistor

OK:

The display is as specified in the normal condition column.

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

C

GO TO STEP 4

A

2.

INSPECT NO. 1 COOLER THERMISTOR (EVAPORATOR TEMPERATURE SENSOR)

(a) Remove the No. 1 cooler thermistor (evaporator temperature sensor).

Click here

(b) Inspect the No. 1 cooler thermistor (evaporator temperature sensor).

Click here

NG

REPLACE NO. 1 COOLER THERMISTOR (EVAPORATOR TEMPERATURE SENSOR)

OK

3.

INSPECT AIR CONDITIONING HARNESS ASSEMBLY (HEATER RADIATOR UNIT SUB-ASSEMBLY)

(a) Remove the air conditioning harness assembly (heater radiator unit sub-assembly)

Click here

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

F7A-38 (TEA) - ev-1

Always

Below 1 Ω

F7A-39 (SGA) - ev-2

Always

Below 1 Ω

F7A-38 (TEA) - F7A-39 (SGA)

Always

10 kΩ or higher

F7A-39 (SGA) or ev-2 - Body ground

Always

10 kΩ or higher

F7A-38 (TEA) or ev-1 - Body ground

Always

10 kΩ or higher

*a

Front view of wire harness connector

(to Air Conditioning Amplifier Assembly)

*b

Front view of wire harness connector

(to No. 1 Cooler Thermistor (Evaporator Temperature Sensor))

OK

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

NG

REPLACE AIR CONDITIONING HARNESS ASSEMBLY (HEATER RADIATOR UNIT SUB-ASSEMBLY)

4.

CHECK FOR DTC

(a) Clear the DTCs.

Click here

Body Electrical > Air Conditioner > Clear DTCs

(b) Check for DTCs.

Click here

Body Electrical > Air Conditioner > Trouble Codes

Result

Proceed to

DTCs are not output

A

DTCs are output

B

A

USE SIMULATION METHOD TO CHECK

B

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

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