GM Service Manual Online
For 1990-2009 cars only
A/C Clutch--Actual: The scan tool displays On/Off. The HVAC control module displays On when the engine control module (ECM) transmits a class 2 message that the A/C compressor clutch relay is energized.

A/C Clutch--Desired: The scan tool displays Yes/No. The scan tool displays Yes when the HVAC control module determines that conditions for compressor clutch engagement are present.

A/C High Side Pressure : The scan tool displays 0-3450 kPa (0-500 psi). The voltage applied to the ECM input from the A/C refrigerant pressure sensor is converted to a pressure value.

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

A/C Pressure: The scan tool displays 0-3450 kPa (0-500 psi). The voltage applied to the ECM input from the A/C refrigerant pressure sensor is converted to a pressure value and transmitted in a class 2 message to the HVAC control module.

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 ECM.

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

Commanded Blower: The scan tool displays 0-100%. The scan tool displays the control decision for the blower motor speed as determined by the HVAC control module. The scan tool displays 100% when the blower motor is commanded to maximum speed. The scan tool displays 0% when the blower motor is commanded OFF.

Coolant Temperature: The scan tool displays -39 to +140°C (-38 to +284°F) . The voltage applied to the ECM input from the engine coolant temperature sensor is converted to a temperature value and transmitted in a class 2 message to the HVAC control module.

Driver Temp Dr. Actual: The scan tool displays 0-255 counts (0-5.00 volts). The voltage applied to the driver air temperature door position input of the HVAC control module.

Driver Temp Dr. Commanded: The scan tool displays 0-255 counts (0-5.00 volts). The desired position of the driver air temperature actuator as determined by the HVAC control module.

Driver Solar Sensor: The scan tool displays 0-255 counts (0-5.00 volts). The voltage applied to the driver sunload input of the HVAC control module.

Driver Sunload: The scan tool displays 0-2000 w/m2. The voltage applied to the driver sunload input of the HVAC control module converted to light intensity units.

ECT Sensor: The scan tool displays -39 to +140°C (-38 to +284°F) . The voltage applied to the ECM 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 ECM input for the engine coolant temperature sensor.

Evaporator Temp: The scan tool displays -39 to +140°C (-38 to +284°F). The voltage applied to the HVAC control module input from the evaporator temperature sensor is converted to a temperature value.

Evaporator Temp: The scan tool displays 0-255 counts (0-5 volts). The voltage applied to the HVAC control module input for the evaporator temperature sensor.

Htr./Def./A/C Dr. Actual: The scan tool displays 0-255 counts (0-5.00 volts). The voltage applied to the mode door position input of the HVAC control module.

Htr./Def./A/C Dr. Commanded: The scan tool displays 0-255 counts (0-5.00 volts). The desired position of the mode actuator as determined by the HVAC control module.

Inside Air Temp.: The scan tool displays -40 to +215°C (-40 to +419°F). The voltage applied to the HVAC control module input for the inside air temperature sensor is converted to a temperature value.

Inside Air Temp.: The scan tool displays 0-255 counts (0-5.00 volts). The voltage applied to the HVAC control module input for the inside air temperature sensor.

Low Coolant Status: The scan tool displays OK/Low. The filtered state of the low coolant switch.

Low Coolant Switch: The scan tool displays Open/Closed. The actual state of the low coolant switch.

Outside Air Temp. : The scan tool displays -40 to +215°C (-40 to +419°F). The current value of the ambient air temperature display on the HVAC control module.

Outside Air Temp. : The scan tool displays 0-255 counts (0-5.00 volts). The voltage applied to the HVAC control module input for the outside air temperature sensor.

Passenger Solar Sensor: The scan tool displays 0-255 counts (0-5.00 volts). The voltage applied to the passenger sunload input of the HVAC control module.

Passenger Sunload: The scan tool displays 0-2000 w/m2. The voltage applied to the driver sunload input of the HVAC control module converted to light intensity units.

Passenger Temp Dr. Actual: The scan tool displays 0-255 counts (0-5.00 volts). The voltage applied to the passenger air temperature door position input of the HVAC control module.

Passenger Temp Dr. Commanded: The scan tool displays 0-255 counts (0-5.00 volts). The desired position of the passenger air temperature actuator as determined by the HVAC control module.

Pressure Sensor: The scan tool displays OK/Failed. The state of the A/C refrigerant pressure sensor and circuitry.