9-5 Linear (9600) L4-2.3L Turbo (2.3t) (2004)
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Cabin Temperature Sensor / Switch: Description and Operation
Cabin Temperature Sensor
The cabin temperature sensor is fitted in the roof panel by the rear-view mirror and is the NTC type. The sensor is supplied with 5 V from K1 pin 16 via
a 10 kohm resistor built into the ACC unit and is grounded from K1 pin 22. This way the voltage over the sensor is inversely proportional to the
temperature (the voltage drops when the temperature rises). The value is used to calculate the current temperature at head height for front seat passenger
and driver. In addition, the following are used as input values:
-
outside temperature
-
time since engine last ran
-
time since start
-
blended-air temperatures
-
fan speed
-
solar irradiance
The cabin temperature sensor's value is only included in the calculation at the start for the ACC unit's regulation. The calculated temperatures are then
compared with those the driver and passenger set with the ACC unit's temperature knob. The set temperature is corrected slightly with respect to the
outside temperature so that the perceived temperature should equal the set temperature.
