Toyota Sienna Quiz
Air conditioning

Evaporator temperature sensor circuit

In this manual: Air conditioning
Introduction — 55Service specifications — 7Maintenance — 7Engine — 264U151e automatic transaxle — 108Transfer — 19Propeller shaft — 8Drive shaft — 14Differential — 16Axle — 18Suspension — 37Tire and wheel — 54Brake control — 141Parking brake — 16Steering Column — 11Power steering — 18Air conditioning — 106Supplemental restraint system — 146Seat belt — 22Theft deterrent — 14Engine immobiliser — 17Cruise control — 65Lighting — 61Wiper and washer — 13Door lock — 42Meter — 28Audio / visual — 94Navigation — 108Park assist / monitoring — 33Horn — 5Garage door opener — 42GR-FE Engine control system — 126Supplemental restraint system — 147Other system — 14Windshield / windowglass — 43Mirror — 23Instrument panel — 6Seat belt — 22Seat — 92Engine hood / door — 104Exterior — 39Interior — 5Sliding roof — 9Multiplex communication — 18Can communication — 23
~2min read

DESCRIPTION

The evaporator temperature sensor (A/C thermistor) is installed on the evaporator in the air conditioning 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.

WIRING DIAGRAM

INSPECTION PROCEDURE

1 READ VALUE OF INTELLIGENT TESTER

(a) Connect the intelligent tester to the DLC3.

(b) Turn the ignition switch to the ON position and turn the intelligent tester main switch on.

(c) Select the item below in the DATA LIST, and read the display on the intelligent tester.

DATA LIST / AIR CONDITIONER:

OK: The display is as specified in the normal condition column.

Result

2 INSPECT EVAPORATOR TEMPERATURE SENSOR

INSPECT EVAPORATOR TEMPERATURE SENSOR

(a) Disconnect the connector from the evaporator temperature sensor.

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

Standard resistance

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 evaporator temperature.

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

3 CHECK HARNESS AND CONNECTOR (EVAPORATOR TEMPERATURE SENSOR - A/C AMPLIFIER)

CHECK HARNESS AND CONNECTOR (EVAPORATOR TEMPERATURE SENSOR - A/C AMPLIFIER)

(a) Disconnect the evaporator temperature sensor connector.

CHECK HARNESS AND CONNECTOR (EVAPORATOR TEMPERATURE SENSOR - A/C AMPLIFIER)

(b) Disconnect the A/C amplifier connector.

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

Standard resistance

REPLACE A/C AMPLIFIER

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