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 B1242 if there is an open circuit in evaporator 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
? Resistance check
? Open Circuit in harness
? Faulty Evaporator sensor
? Faulty A/C Control Unit
Threshold value
? <2.4?
Detecting time
? 0.3sec
FAIL SAFE
? Control with the value of 20?
? Resistance value of evaporator sensor as a function of temperature.
Temperature(?)
Resistance(?)
-10
43.3
20
12.1
0
27.6
30
8.3
10
18
40
5.8