GM Service Manual Online
For 1990-2009 cars only
A/C Pressure Sensor: The scan tool displays 0-3450 kPa (0-500 psi). The voltage applied to the PCM input from the A/C refrigerant pressure sensor is converted to a pressure value.

A/C Pressure Sensor: The scan tool displays 0-5 volts. The voltage applied to the PCM input for the A/C refrigerant pressure sensor.

A/C Switch: The scan tool displays On/Off. The scan tool displays On when the A/C request switch is active. The scan tool displays Off when the A/C request switch is inactive.

A/C Relay Command: The scan tool displays On/Off. The scan tool displays the control decision for the compressor clutch relay output as determined by the PCM.

A/C Request Signal: The scan tool displays Yes/No. The scan tool displays Yes when the PCM receives a class 2 message from the HVAC control module to engage the A/C compressor clutch. The scan tool displays No when the PCM receives a class 2 message from the HVAC control module to disengage the A/C compressor clutch.

Air Mix Door Left Commanded: The scan tool displays 0-255 counts. The scan tool displays the desired left air temperature door position as determined by the HVAC control module.

Air Mix Door Right Commanded: The scan tool displays 0-255 counts. The scan tool displays the desired right air temperature door position as determined by the HVAC control module.

Battery Voltage: The scan tool displays 0-25 volts. The voltage measured from the battery positive voltage circuit and the ground circuit of the HVAC control module.

ECT Sensor: The scan tool displays -39 to 140°C (-38 to 284°F) . The voltage applied to the PCM input from the engine coolant temperature sensor is converted to a temperature value.

ECT Sensor: The scan tool displays 0-5 volts. The voltage applied to the PCM input for the engine coolant temperature sensor.

Ign. Since Current DTC: The scan tool displays 0-100. The number of the ignition cycles since the setting of the most recent current diagnostic trouble code (DTC).

Left Mix Door Actual: The scan tool displays 0-255 counts. The voltage applied to the left air temperature door position input of the HVAC control module is converted to a number between 0 - 255 where 51 Counts is approximately equal to 1 volt.

Left Mix Motor Drive: The scan tool displays Stop, Increase, or Decrease. The scan tool displays the control decision for the actuator output as determined by the HVAC control module.

Left Temp. Detent Pos.: The scan tool displays 0 to 18. The scan tool displays the position of the left air temperature switch.

Mode Door Actual: The scan tool displays 0-255 Counts. The voltage applied to the HVAC control module input for the mode door position is converted to a number between 0 - 255 where 51 Counts is approximately equal to 1 volt.

Mode Door Commanded: The scan tool displays 0-255 counts. The scan tool displays the desired mode door position as determined by the HVAC control module.

Mode Motor Drive: The scan tool displays Stop, Increase, or Decrease. The scan tool displays the control decision for the actuator output as determined by the HVAC control module.

Mode Select Position: The scan tool displays Off, Defrost, Heater, Htr/Def, Bi-Level, Panel. The scan tool displays the state of mode operation.

Pressure Cycle Switch: The scan tool displays Low Pressure/Normal. The current state of the input from the A/C low pressure switch. The scan tool displays Low Pressure when the switch is open and displays Normal when the switch is closed. The low pressure switch opens when low side pressure decreases to approximately 151 kPa (22 psi) and closes when the low side pressure increases to approximately 275 kPa (40 psi).

Recirculate Switch: The scan tool displays On/Off. The scan tool displays On when the recirculation switch is active. The scan tool displays Off when the recirculation switch is inactive.

Right Mix Door Actual: The scan tool displays 0-255 counts. The voltage applied to the right air temperature door position input of the HVAC control module is converted to a number between 0 - 255 where 51 Counts is approximately equal to 1 volt.

Right Motor Drive: The scan tool displays Stop, Increase, or Decrease. The scan tool displays the control decision for the actuator output as determined by the HVAC control module.

Right Temp. Detent Pos.: The scan tool displays 0 to 18. The scan tool displays the position of the right air temperature switch.