The ambient temperature sensor located at the center stay of the condensor detects ambient air temperature. It is joined to AQS sensor as one boby. It is a negative type thermistor whose resistance is inversely proportional to temperature. Its output is used for sensor fail-safe, temperature regulation door lock, blower motor level control, mix mode control and in-car humidity control.
The ECM sets DTC B1238 if there is an open circuit in ambient temp sensor signal harness or the measured voltage value of the sensor is more than the threshold value(4.9V)
Item | Detecting Condition | Possible Cause |
DTC Strategy | ● Voltage check | ● Open Circuit in harness ● Faulty ambient temp.sensor ● Faulty A/C Control Unit |
Threshold value | ●< 4.9V | |
Detecting time | ● 0.3sec | |
FAIL SAFE | ● Control with the value of 20℃ |
※ Resistance value of ambient temp.sensor as a function of temperature.
Temperature(℃) | Resistance(㏀) | Temperature(℃) | Resistance(㏀) |
-20 | 271.1 | 50 | 10.9 |
0 | 95.1 | 60 | 7.5 |
25 | 30.0 | ||
