Air Conditioning Evaporator Temperature (ACET) Sensor
WARNING: This page does not describe the selected car, but rather 35 other vehicles, including the 2007 Mercury Mountaineer, 2007 Mercury Monterey, 2007 Mercury Montego, 2007 Mercury Milan, and 2007 Mercury Mariner. However, it is still accessible from the selected car via links, so may be relevant.
The ACET sensor measures the evaporator air discharge temperature. The ACET sensor is a thermistor device in which resistance changes with temperature. The electrical resistance of a thermistor decreases as the temperature increases, and the resistance increases as the temperature decreases. The PCM sources a low current 5 volts on the ACET circuit. With SIG RTN also connected to the ACET sensor, the varying resistance changes the voltage drop across the sensor terminals. As A/C evaporator air temperature changes, the varying resistance of the ACET sensor changes the voltage the PCM detects.
The ACET sensor is used to more accurately control A/C clutch cycling, improve defrost/demist performance, and reduce A/C clutch cycling.
NOTE:
These values can vary 15% due to sensor and VREF variations. Voltage values were calculated for VREF equals 5.0 volts.
A/C EVAPORATOR TEMPERATURE (ACET) SENSOR VOLTAGE AND RESISTANCE
| °C | °F | Volts | Resistance (K ohms) |
|---|---|---|---|
| 100 | 212 | 0.47 | 2.08 |
| 90 | 194 | 0.61 | 2.80 |
| 80 | 176 | 0.80 | 3.84 |
| 70 | 158 | 1.05 | 5.34 |
| 60 | 140 | 1.37 | 7.55 |
| 50 | 122 | 1.77 | 10.93 |
| 40 | 104 | 2.23 | 16.11 |
| 30 | 86 | 2.74 | 24.25 |
| 20 | 68 | 3.26 | 37.34 |
| 10 | 50 | 3.73 | 58.99 |
| 0 | 32 | 4.14 | 95.85 |
| -10 | 14 | 4.45 | 160.31 |
| -20 | -4 | 4.66 | 276.96 |