The Evaporator sensor located on heater unit detects the core temperature. It is a negative type thermistor whose resistance is inversely proportional to temperature. Evaporator sensor transforms measured temperature into voltage value and delivers it to A/C ECU. when core temperature is blow threshold value, A/C ECU interrupts compressor relay power, in order to prevent evaporator freezing by excessive cooling.
Air conditioner Control Module sets DTC B1242 if Evaporator sensor has been detected over 4.9V for 4 seconds.
Item | Detecting Condition | Possible Cause |
DTC Strategy |
•
Voltage check | 1. Open in signal circuit 2. Short to battery in signal circuit 3. Faulty Evaporator sensor 4. Faulty Air conditioner control Unit |
Enable Conditions |
•
IG KEY ON | |
Threshold value |
•
Evaporator sensor has been detected over 4.9V for 4 seconds | |
Failsafe |
•
Control with the value of -2℃(28.4℉) |
Temperature(℃/℉) | Resistance(㏀) | Temperature(℃/℉) | Resistance(㏀) |
-10/-14 | 18 | 20/68 | 4.8 |
0/32 | 11 | 30/86 | 3.3 |
10/50 | 7.3 | 40/104 | 2.3 |
