Air Temperature Sensor ( Ambient / Intake ): Description and Operation

Air Charge Temperature (ACT) Sensor:

PURPOSE
The Air Charge Temperature (ACT) sensor provides the Electronic Control Assembly (ECA) with mixture (fuel and air) temperature information.

LOCATION
The ACT sensor is threaded into the intake air passage with a sensing element extending into the air chamber.

CONSTRUCTION
The ACT sensor is a negative temperature coefficient sensor. As sensor temperature increases, resistance values decrease.

OPERATION
The sensor is used both as a density corrector for airflow calculations and to proportion the cold enrichment fuel flow.

Varying resistance affects the voltage drop across the sensor terminals and provides electrical signals to the ECA corresponding to engine temperature. A cold engine results in a high electrical signal.

ACT resistances:

-40° 269 K ohms

32° 95 K ohms

77° 29 K ohms

248° 1.2 K ohms