Escape 2WD L4-2.5L (2009)
Evaporator Temperature Sensor / Switch: Description and Operation
Air Conditioning
Air Conditioning
Evaporator Discharge Air Temperature Sensor
NOTE: A second (auxiliary) evaporator discharge air temperature sensor is used for the auxiliary evaporator core on hybrid vehicles.
The evaporator discharge air temperature sensor contains a thermistor. The resistance of this thermistor varies by a specific amount based on the
evaporator discharge air temperature. The HVAC module measures a voltage ratio between the reference voltage it supplies to the sensor and the sensor
return voltage to determine this resistance and the associated discharge air temperature.
The evaporator discharge air temperature sensor maintains evaporator core temperature and prevents icing of the evaporator core. It does this by
signaling the HVAC module to switch off the A/C request signal to the instrument cluster on 2.5L or 3.0L (4V) vehicles, or signaling the PCM to cycle
the A/C compressor off when the evaporator discharge air temperature sensor reading falls below acceptable levels. The A/C request or A/C compressor
will be switched back on when the evaporator temperature rises above acceptable levels.
On hybrid vehicles, the A/C compressor will continue to run and the passenger zone valve will be closed by the PCM if the evaporator discharge air
temperature sensor is reading a temperature below acceptable levels, but the TBCM is requesting A/C operation for HVTB cooling. This allows
continued refrigerant flow to the auxiliary evaporator core while allowing the front (main) evaporator core to warm to acceptable levels.
The evaporator discharge air temperature sensor is located on the heater core and evaporator core housing behind the glove compartment.
