Manual Air Conditioning

AIR CONDITIONING: AIR CONDITIONING SYSTEM (for Manual Air Conditioning System): B1412/12: Ambient Temperature Sensor Circuit
B1412/12 - 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

PROCEDURE

1. READ VALUE USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON and turn the Techstream ON.

(c) Select the item below in the Data List, and read the value displayed on the Techstream.

Air conditioning amplifier:





OK:

The display is as specified in the normal condition column.

Result:





C -- REPLACE AIR CONDITIONING AMPLIFIER

B -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
A -- Continue to next step.

2. INSPECT AMBIENT TEMPERATURE SENSOR





(a) Remove the ambient temperature sensor.

(b) 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).

NG -- REPLACE AMBIENT TEMPERATURE SENSOR
OK -- Continue to next step.

3. CHECK WIRE HARNESS (AMBIENT TEMPERATURE SENSOR - COMBINATION METER)





(a) Disconnect the A17 sensor connector.

(b) Disconnect the E19 meter connector.

(c) Measure the resistance of the wire harness side connectors.

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR

OK -- REPLACE COMBINATION METER