The HVAC Scan Tool Data Definitions contain a brief description of all the scan tool parameters. This list is in alphanumeric order.

A/C High Side Pressure : The scan tool displays 0 to 4000 kPa (0 to 580 psi). This parameter represents the A/C refrigerant pressure sensor voltage signal converted to pressure.

A/C High Side Pressure : The scan tool displays 0.00-5.00 Volts. This parameter represents the A/C refrigerant pressure sensor signal.

A/C Off For WOT : The scan tool displays Yes or No. Yes indicates that the PCM has disabled the A/C compressor because the TP sensor signal is at wide open throttle.

A/C Pressure Disable : The scan tool displays Yes or No. Yes indicates that the PCM has disabled the A/C compressor due to excessive refrigerant pressure.

A/C Relay Circuit Status: The scan tool displays OK, Fault or Invalid. Represents the status of the A/C relay circuit.

A/C Relay Commanded: The scan tool displays On or Off. Represents the PCM commanded state of the A/C compressor clutch relay. The A/C compressor clutch should be engaged when A/C Relay Commanded displays On.

A/C Request Signal: The scan tool displays Yes or No. The PCM uses the A/C request signal in order to determine if A/C compressor operation is being requested by the HVAC control module.

ECT Sensor: The scan tool displays a range of -40 to 215°C (-40 to 420°F). The powertrain control module (PCM) applies 5.0 volts to the ECT sensor circuit. The sensor is a thermistor which changes internal resistance as the engine temperature changes. When the sensor is cold, internal resistance is high, the PCM senses a high volage signal 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.