Temperature Sensor For Fresh Air Intake

Temperature Sensor for Fresh Air Intake

The fresh air intake temperature serves as a reference variable to control the compressor. The outside temperature also serves as a control variable. This value is supplied from the front end control unit via the CAN bus. The lower of the two measurements from the fresh air intake sensor or the outside air sensor (behind the ribs on the right hand opening at the front end) is employed to assess the system (system outside temperature).

In the case of a falling temperature, assessment of the system outside temperature is subject to a time constant of t = 1 second. When the system outside temperature rises, a vehicle speed dependent filter is employed. At speeds under 9.3 mph (15 km/h), the evaluation of temperature changes is "frozen". A change to the temperature value will only be accepted if the speed exceeds 9.3 mph (15 km/h) for a duration of at least t = 2 seconds. This prevents stop and go traffic from leading to incorrect system outside temperature values (incorrect measurements due to heat emitted from the engine, for example).