Heater Temperature Sensor
WARNING: This page is about a different car, the 2006 Land Rover Range Rover. However, it is still accessible from the selected car via links, so may be relevant.
The heater temperature sensor is a NTC thermistor that provides the ATC module with a temperature signal from the air outlet side of the heater core. On manual systems, a single sensor is installed in the rear of the heater assembly casing, to the right of the center-line. On automatic systems, two sensors are installed, one each side of the center-line.
The ATC module uses the input from the heater temperature sensor(s) to control the operation of the coolant valve(s).
The signal voltage from each heater temperature sensor is between 0 and 5 V. The ATC module monitors the signal voltage and defaults to a temperature of 55°C (131°F) if it goes out of the range 0.173 - 4.890 V:
- If the signal voltage is less than 0.173 V, the ATC module assumes there is a short circuit to ground
- If the signal voltage is more than 4.890 V, the ATC module assumes there is an open circuit or a short circuit to battery.