GM Service Manual Online
For 1990-2009 cars only
Table 1: HVAC Control Module Scan Tool Output Controls
Table 2: ECM Scan Tool Output Controls

HVAC Control Module Scan Tool Output Controls

The Enable condition: Key On / Engine Off

Scan Tool Output Control

Additional Menu Selections

Description

A/C Request

Output Control

When you select A/C request, this command allows you to turn the A/C Relay On and Off. When the A/C Relay is commanded On, the A/C compressor clutch should be engaged.

Air Inlet Door Position

Output Control

When you select Outside, the HVAC control module commands the recirculation actuator toward the outside air position. When you select Recirc, the HVAC control module commands the recirculation actuator toward the recirculation position. This is shown through a command of On and Off.

Blower Motor

Output Control

When you select ON, the HVAC control module commands the blower motor relay ON and a command to increase or decrease air. When you select OFF, the HVAC control module commands the blower motor relay OFF.

Auxiliary Blower Motor

Output Control

When you select ON, the HVAC control module commands the blower motor relay ON and an increase or decrease of air. When you select OFF, the HVAC control module commands the blower motor relay OFF.

Left Temp Door Position

Output Control

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

Auxiliary Air Temp Door

Output Control

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

Mode Door Position

Output Controls

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

Auxiliary Mode Door Position

Output Controls

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

Passenger Temp Door Position

Output Controls

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.

Rear Defog Request

Output Controls

The BCM must receive a Rear Defog request from the HVAC control module in order to enable the output control. The BCM de-energizes the Rear Defog Relay located in the I/P BEC when you select OFF. The relay remains de-energized until you select ON.

Recalibrate All Motors

Output Control

When you select On, all air temp, and mode actuators have the capability to perform a recalibration.

ECM Scan Tool Output Controls

The Enable Condition: Key On / Engine On

Scan Tool Output Control

Additional Menu Selections

Description

A/C Request

Output Controls

The engine must be running and the ECM must receive an A/C request from the HVAC control module in order to enable the output control. The ECM de-energizes the A/C compressor clutch relay when you select OFF. The relay remains de-energized until you select ON.