The incar temperature sensor joined to Humidity sensor as one body is located at heater control unit. It contains a thermistor which measures the temperature of the inside. The signal,decided by the resistance value which changes in accordance with perceived inside temperature, is delivered to heater control unit.
According to this signal, the control unit regulates incar temperature to intended value.
The ECM sets DTC B1234 if there is an open circuit in incar 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 incar temp.sensor
? Faulty A/C Control Unit
Threshold value
?< 4.9V
Detecting time
? 0.3sec
FAIL SAFE
? Control with the value of 25?
? Resistance value of incar temp sensor as a function of temperature.
Temperature(?)
Resistance(?)
Min
Mid
Max
-15
209.2
216.1
223.0
0
95.4
97.7
100.1
15
46.3
47.1
47.9
25
29.6
30.0
30.4
35
19.3
19.6
19.9
50
10.6
10.8
11.0