B1412

AIR CONDITIONING: AIR CONDITIONING SYSTEM: B1412/12: Ambient Temperature Sensor Circuit

DTC 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 air conditioning amplifier 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. 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.






WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. READ VALUE USING TECHSTREAM (AMBIENT TEMPERATURE SENSOR)
(a) Connect the Techstream to DLC3.
(b) Turn the ignition switch ON.
(c) Turn the tester on.
(d) Select the following menus: Body Electrical / Air Conditioner / Data List / Ambient Temp Sensor
(e) According to the display on tester, read the "Data List".
Data List / Air Conditioner:






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.
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 on the left).
(c) Reinstall the ambient temperature sensor.
NG -- REPLACE AMBIENT TEMPERATURE SENSOR
OK -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (AMBIENT TEMPERATURE SENSOR - AIR CONDITIONING AMPLIFIER)




(a) Disconnect the B5 ambient temperature sensor connector.
(b) Disconnect the E8 air conditioning amplifier connector.
(c) Measure the resistance.
Standard resistance:





(d) Reconnect the ambient temperature sensor connector.
(e) Reconnect the air conditioning amplifier connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE AIR CONDITIONING AMPLIFIER