Cabin Temperature Sensor / Switch: Description and Operation

Cabin Temperature Sensor












The cabin temperature sensor is positioned in the dashboard under the ACC unit. The unit has a built-in suction fan that draws cabin air past an NTC resistor.

The cabin temperature sensor in the most important value for the ACC unit and is compared to the cabin temperature in order to decide if the mixed-air temperature should be increased or decreased.

The cabin temperature is adjusted with respect to the outside temperature so that the temperature experienced matches the set temperature. As the difference between selected temperature and adjusted temperature increases, the ventilation fan speed will also increase.

When the ignition is turned off, the suction fan will continue to operate for approximately 10 minutes. This decreases the risk of incorrect temperature value when restarting after a short stop.

IMPORTANT
The cabin temperature gives an incorrect value if the cigarette lighter/cover is not fitted. This is due to warm air being drawn from the rear of the dashboard through the socket for the cigarette lighter and into the cabin temperature sensor. The cabin temperature sensor must not be positioned in any other location in the dashboard.

Diagnosis
In case of an open circuit or short circuit, diagnostic trouble code B1350 is generated, and 02 is shown instead of temperature at calibration.

The outside temperature is used as replacement value when the ignition is turned on and then the calculated head level temperature for the front seat passenger and driver is used.