Scan Tool Data Definitions

WARNING: This page is about a different car, the 2004 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.

AC Clutch: The parameter indicates On whenever the powertrain control module (PCM) energizes the A/C compressor clutch relay. Engaging the A/C compressor clutch relay will also engage the cooling fan at low speed.
AC Request Signal: This parameter indicates whether the A/C switch on the instrument panel (IP) has been selected.
ECT Sensor: The scan tool range is -40 to +140° C (-40 to +284° F). The engine coolant temperature (ECT) sensor is a thermistor which changes internal resistance as the temperature changes. When the sensor is cold, internal resistance high, the powertrain control module (PCM) monitors a high signal voltage and interprets the voltage as a cold engine. As the sensor warms, internal resistance decreases, the voltage signal decreases and the PCM interprets the lower voltage as a warm engine.