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 B1237 if there is a short circuit in ambient temp sensor signal harness or the measured voltage value of the sensor is less than the threshold value.(0.1V)
Item
Detecting Condition
Possible Cause
DTC Strategy
? Voltage check
? Short circuit in harness
? Faulty ambient temp.sensor
? Faulty A/C Control Unit
Threshold value
? <0.1V
Detecting time
? 0.3sec
FAIL SAFE
? Control with the value of 20°C
? Resistance value of ambient temp.sensor as a function of temperature.
Temperature(°C)
Resistance(k?)
-20
271.4
50
11
0
95.1
80
3.8
25
30