GM Service Manual Online
For 1990-2009 cars only

HVAC Control Module Scan Tool Output Controls

Scan Tool Output Control

Additional Menu Selections

Description

Air Inlet Door Position

HVAC Motors

When you select Outside, the HVAC control module commands the recirculation actuator toward the outside air position. When you select Recirculation, the HVAC control module commands the recirculation actuator toward the recirculation position.

Blower Motor

Miscellaneous Test

When you select ON, the HVAC control module commands the blower motor relay ON. When you select OFF, the HVAC control module commands the blower motor relay OFF.

Driver Temp Door Position

HVAC Motors

When you select Cold, the HVAC control module commands the driver air temperature actuator to the full cold position. When you select Hot, the HVAC control module commands the actuator to the full hot position.

Mode Door Position

HVAC Motors

When you select A/C, the HVAC control module commands the mode actuator to the face position. When you select Defrost, the HVAC control module commands the actuator to the defrost position.

Passenger Temp Door Position

HVAC Motors

When you select Cold, the HVAC control module commands the passenger air temperature actuator to the full cold position. When you select Hot, the HVAC control module commands the actuator to the full hot position.

HVAC Scan Tool Data Parameters

Parameter

Operating Conditions

Expected Value

Definition

Ignition is ON, engine OFF, and vehicle is stationary

A/C Compressor Current

--

0.008 A

This parameter displays the current of the air conditioning (A/C) Compressor.

A/C Compressor PWM

--

0 - 100%

This parameter displays the percentage of power supplied to the A/C compressor.

A/C Mode Request

--

Disengaged

The scan tool displays Engage or Disengage. Engaged is displayed if the A/C is requested.

--

Engaged

A/C Pressure

--

448 kpa

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

A/C Switch

A/C button pressed

Active

The scan tool displays Active or Inactive. The scan tool displays Active when the A/C request switch is On. The scan tool displays Inactive when the A/C request switch is Off.

A/C button depressed

Inactive

Actual Air Mix Door Position

--

0 - 100%

This displays 0 - 100%. The actual position of air mix door is interpreted as a percentage by the HVAC control module.

Actual Front Demister Door Pos.

--

0 - 100%

The scan tool displays 0 - 100 %. The actual position of the front demister door is interpreted as a percentage by the HVAC control module.

Actual Recirculation Door Position

--

0 - 100%

The scan tool displays 0 - 100 %. The actual position of the recirculation door is interpreted as a percentage by the HVAC control module.

Actual Vent/Floor Outlet Door Pos.

--

0 - 100%

The scan tool displays 0 - 100 %. The actual position of the vent/floor outlet door interpreted as a percentage by the HVAC control module.

Backup System Power Mode

Backup system power mode activated

Enable

This parameter displays the status of the backup system power mode

Backup system power mode deactivated

Disable

Battery Voltage

--

0 - 25 Volts

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.

Blower Fan Speed Dial

User Dependent

0 - 100%

The scan tool displays 0 - 100%. The speed of the blower motor is interpreted as a percentage.

Blower Fan Speed PWM

--

0 - 114%

The scan tool displays 0 - 114%. The scan tool displays the control decision for the blower motor speed as determined by the HVAC control module. The scan tool displays 114% when the blower motor is commanded to maximum speed and 0% when the blower motor is commanded Off.

Blower Fan Speed Voltage

--

1.4 Volts

The scan tool displays a voltage. The scan tool displays the control decision for the blower motor speed as determined by the HVAC control module. The scan tool displays 1.4 Volts when the blower motor is commanded to maximum speed and 0 Volts when the blower motor is commanded Off.

Commanded Air Mix Door Position

--

0 - 100%

The scan tool displays 0 - 100%. The commanded position of the air mix door interpreted as a percentage by the HVAC control module.

Commanded Front Demister Door Pos.

--

0 - 100%

The scan tool displays 0 - 100%. The commanded position of the front demister door interpreted as a percentage by the HVAC control module.

Commanded Recirculation Door Pos.

--

0 - 100%

The scan tool displays 0 - 100 %. The commanded position of the recirculation door interpreted as a percentage by the HVAC control module.

Commanded Vent/Floor Outlet Door Pos.

--

0 - 100%

The scan tool displays 0 - 100 %. The commanded position of the vent/floor outlet door interpreted as a percentage by the HVAC control module.

Engine Coolant Temp

--

18 degrees

The scan tool displays -39 to +140°C (-38 to +284°F). The scan tool displays the engine coolant temperature as detected by the ECM.

Engine ECU A/C Compressor Command

--

Allowed

This parameter indicates permission to turn On the A/C Compressor from the ECM. The scan tool displays Allowed or Not Allowed.

--

Not Allowed

Engine Speed

--

0 RPM

The scan tool displays the speed of the engine in RPM.

Evaporator Target Temp

--

-40 degrees

This parameter displays the target temperature of the evaporator as set by the HVAC control module

Evaporator Temp

--

15 degrees

This parameter displays the current temperature of the evaporator

Evaporator Temp

--

15.5 degrees

This parameter displays the current temperature of the evaporator

Front Outlet Mode

User dependent

Compartment

The scan tool displays Compartment, Compartment/Floor, Floor, Floor/Demister or Demister. This is the front outlet mode as interpreted by the HVAC control module.

Compartment/Floor

Floor

Floor/Demister

Demister

Inlet Mode

Recirculation button pressed

Recirculation

The scan tool displays Fresh or Recirculation. This is the inlet mode as interpreted by the HVAC control module.

Recirculation button depressed

Fresh

Mode Dial

Mode Dial in Compartment position

Compartment

The scan tool displays Floor, Compartment or Demister. This is the outlet mode as selected by the user and is interpreted by the HVAC control module.

Mode Dial in Compartment/Floor position

Compartment/Floor

Mode Dial in Floor position

Floor

Mode Dial in Floor/Demister position

Floor/Demister

Mode Dial in Demister position

Demister

Rear Window Demister

Rear window demister activated

Active

The scan tool displays the status of the rear window demister, Active when the rear window demister is activated and Inactive when the rear window demister is deactivated.

Rear window demister deactivated

Inactive

Rear Window Demister Switch

Rear window demister switch activated

Active

The scan tool displays the current position of the rear window demister switch, Active when the rear window demister switch is activated and Inactive when the rear window demister switch is deactivated.

Rear window demister switch deactivated

Inactive

Recirculation Switch

Recirculation switch activated

Active

The scan tool displays the current position of the recirculation switch, Active when the recirculation switch is activated and Inactive when the recirculation switch is deactivated.

Recirculation switch deactivated

Inactive

System Power Mode

Ignition is in OFF position

OFF

The scan tool displays the system power mode which is dependent on the current position of the ignition cycle.

Ignition is in ACC position

Accessory

Ignition is in RUN position

Run

Ignition is in CRANK position

Crank

Temperature Dial

--

0 - 100%

The scan tool displays 0 - 100%. The temperature position is commanded by the user and is interpreted as a percentage by the HVAC control module.

Vehicle Speed

--

0km

The scan tool range is 0 - 255 km/h (0 - 158 mph). This parameter indicates the vehicle speed calculated by the ECM from the vehicle speed sensor (VSS).