Toyota RAV4 Service Manual: Ambient temperature sensor circuit
Description
The ambient temperature sensor is installed in the front part of the condenser to detect the ambient temperature and control the air conditioner. The sensor is connected to the combination meter and detects fluctuations in the ambient temperature. This data is used for controlling the room temperature.
The sensor sends a signal to the air conditioning amplifier via the combination meter. The resistance of the ambient temperature sensor changes in accordance with the ambient temperature. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.
The air conditioning amplifier applies a voltage (5 v) to the ambient temperature sensor and reads voltage changes as changes in the resistance of the ambient temperature sensor. The combination meter sends the read signal to the air conditioning amplifier via can communication.
Wiring diagram
Inspection procedure
- Read value of intelligent tester (ambi temp sens)
- Connect the intelligent tester (with can vim) to the dlc3.
- Turn the ignition switch on and turn the intelligent tester main switch on.
- Select the item below in the data list, and read the value displayed on the intelligent tester.
Ok: the display is as specified in the normal condition column.
- Inspect ambient temperature sensor
- Remove the ambient temperature sensor.
- Measure the resistance of the sensor.
Standard resistance 
Notice:
- Touching the sensor even slightly 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).
- Check wire harness (ambient temperature sensor - combination meter)
- Disconnect the a17 sensor connector.
- Disconnect the e19 meter connector.
- Measure the resistance of the wire harness side connectors.
Standard resistance 
Replace combination meter
Room temperature sensor circuit
Description
The room temperature sensor is installed in the instrument panel to detect
the room temperature and
control the heater and air conditioner auto mode. The resistance of the room
t ...
Evaporator temperature sensor circuit
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 ...
Other materials:
Air conditioning amplifier communication stop mode
Description
Wiring diagram
Inspection procedure
Notice:
Turn the ignition switch off before measuring the resistances
of the main wire and the branch
wire.
After the ignition switch is turned off, check that the key
reminder warning system and light
reminder warning sy ...
Disassembly
Caution:
Wear protective gloves. Sharp areas on the seat frame
(with adjuster) may injure your hands.
Hint:
Use the same procedures for the rh side and lh side.
The procedures listed below are for the lh side.
Remove vertical adjuster cover lh (for driver side)
Using a screw ...
Diagnosis system
Description
The occupant classification ecu controls the functions of
the occupant classification system on the vehicle. Data
of the occupant classification system can be read in the
data link connector 3 (dlc3) of the vehicle. When the
system seems to be malfunctioning, use the intelligen ...