Aurora V6-214 3.5L VIN H SFI (2001)
Cabin Temperature Sensor / Switch: Description and Operation
TEMPERATURE SENSORS
The automatic system uses multiple sensors to achieve and maintain the desired temperature. The inside air temperature sensor provides the IPM
software with the temperatures of the air drawn through the aspirator. A 5-volt reference signal is sent from the IPM to the inside air temperature sensor
over the inside air temperature sensor signal circuit. A thermister inside the sensor varies the voltage. That varied voltage provides a signal to the
software inside the IPM. As the air temperature increases, resistance decreases. Remaining voltage from the inside air temperature sensor is sent back to
the IPM ground through the low reference circuit. The lower left air temperature sensor provides the IPM software with the temperature of the air exiting
from the left closeout/insulator panel. A 5-volt reference signal is sent from the IPM to the lower left air temperature sensor over the lower left air
temperature sensor signal circuit. A thermister inside the sensor varies the voltage. That varied voltage provides a signal to the software inside the IPM.
Remaining voltage from the lower left air temperature sensor is sent back to the IPM ground through the low reference circuit.
The lower right air temperature sensor provides the IPM software with the temperature of the air exiting from the right closeout/insulator panel. A 5-volt
reference signal is sent from the IPM to the lower right air temperature sensor over the lower right air temperature sensor signal circuit. A thermister
inside the sensor varies the voltage. That varied voltage provides a signal to the software inside the IPM. Remaining voltage from the lower right air
temperature sensor is sent back to the IPM ground through the low reference circuit.
The upper left air temperature sensor provides the IPM software with the temperature of the air exiting from the left A/C duct. A 5 volt reference signal
is sent from the IPM to the upper left air temperature sensor over the upper left air temperature sensor signal circuit. A thermister inside the sensor varies
the voltage. That varied voltage provides a signal to the software inside the IPM. Remaining voltage from the upper left air temperature sensor is sent
back to the IPM ground through the low reference circuit.
The upper right air temperature sensor provides the IPM software with the temperature of the air exiting from the right A/C duct. A 5 volt reference
signal is sent from the IPM to the upper right air temperature sensor over the upper right air temperature sensor signal circuit. A thermister inside the
sensor varies the voltage. That varied voltage provides a signal to the software inside the IPM. Remaining voltage from the upper right air temperature
sensor is sent back to the IPM ground through the low reference circuit.
The ambient air temperature sensor provides the IPM software with the temperature of the air outside the vehicle and displays that temperature on the
HVAC control module. A 5-volt reference signal is sent from the IPM to the ambient air temperature sensor over the ambient air temperature sensor
signal circuit. A thermister inside the sensor varies the voltage. That varied voltage provides a signal to the software inside the IPM. As the air
temperature increases, resistance decreases. Remaining voltage from the ambient air temperature sensor is sent back to the IPM ground through the low
reference circuit.
Since the sensor is mounted underhood, it can be affected by city traffic, idling, and hot engine restarts. A temperature memory feature is used in the IPM
ambient air temperature programming to help provide greater accuracy under engine restart conditions. If the engine coolant temperature is not more
than 10°C (18°F) above the ambient air temperature sensor reading, or if the engine has not been started in two hours, then the actual ambient air
temperature sensor reading is displayed. However, if the engine coolant is more than 10°C (18°F) above the sensor reading, the memorized ambient air
temperature is displayed. This is the last displayed temperature sensed when the engine was operating. At vehicle speeds greater than 16 km/h (10 mph),
the ambient air temperature displayed may be allowed to increase, but only after a built-in 300-second time delay which allows for ambient air to cool
the sensor. The time delay starts when vehicle speed reaches or maintains at least 16 km/h (10 mph). If the sensor reading is ever less than the displayed
value, then the ambient air temperature changes are displayed as rapidly as possible.
