Air Temperature Switch: Description and Operation

Electronic Components:

DESCRIPTION
The Intake Manifold Air Temperature Sensor is a variable, thermistor type. It reacts to temperature changes. At cold air temperatures, its resistance is high. As temperatures increase, its resistance will decrease.

OPERATION
The air temperature sensor element extends into the intake manifold air stream. It provides an input voltage to the Powertrain Control Module (PCM) indicating intake manifold air temperature. The input from this sensor is used by the PCM to determine if and how long to activate the intake manifold air heater relays. When the relays are activated, current will flow through the relays to the intake manifold air heater.

As the temperature of the air-fuel stream in the manifold varies, the sensor resistance will change. This will result in a different input voltage to the PCM.