9000 CS L4-2290cc 2.3L DOHC Turbo EFI (1996)
Cabin Temperature Sensor / Switch: Description and Operation
In Car Temperature Sensor (Cabin Temperature Sensor)
The sensor has a built-in suction fan which sucks cabin air past an NTC resistor. NTC stands for Negative Thermal Coefficient and means that
resistance decreases as temperature rises.
The sensor is powered from pin 33 and grounded on pin 15 on the ACC control module. The suction fan is supplied with voltage from pin 16 on
the ACC control module and is grounded to grounding point G8.
The cabin temperature is the ACC control module's most important measured value and is compared with the selected cabin temperature to decide
if the blended-air temperature should be raised or lowered.
Cabin temperature is adjusted with reference to the outside temperature to achieve the physical sensation of the selected temperature. If the
difference between the selected temperature and the adjusted cabin temperature increases, the speed of the ventilation fan will also increase.
As heat behind the facia affects the reading from the cabin temperature sensor during short stops, the ACC control module re-checks the reading
45 seconds after the engine has been started.
For the same reason, the sensor suction fan continues to suck air through the sensor for 4 minutes after the ignition has been switched off.
Both these features reduce the risk of erroneous data.
If there is no reading from the cabin temperature sensor, temperature is set at +18 °C (64.5 °F).
