GM Service Manual Online
For 1990-2009 cars only

Object Number: 387870  Size: MF
HVAC Components
Cell 68: Vacuum Tank - Pontiac
Cell 68: Passenger Air Mix Actuator - Oldsmobile, Buick
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The HVAC programmer commands the actuator to move by suppling battery voltage. The feedback supplied to the HVAC programmer is a regulated 5 volts. The feedback voltage is a function of the motor position with a high voltage of 4-5 volts indicating full cold door position. A low voltage of less than 1 volt indicates the full hot position. Operation of the air mix door actuator can be evaluated through the Scan Tool .

Conditions for Setting the DTC

The ignition is ON.

Action Taken When the DTC Sets

Only the full hot or full cold may be used by the system.

Conditions for Clearing the DTC

    • Using a Scan Tool .
    • A history DTC will clear when 40 consecutive ignition cycles have occurred without a malfunction.
    • HVAC programmer battery voltage is interrupted.

Step

Action

Value(s)

Yes

No

1

  1. Turn the ignition switch to the RUN position.
  2. Set the Scan Tool in order to "HVAC TESTS"--Data Pair for Mix Door #1.
  3. Set the temperature to full cold.

Does the Scan Tool show a commanded (COM) mix door position that matches the specified value?

100%

Go to Step 2

Go to Step 6

2

Set the temperature to full hot.

Does the Scan Tool show a commanded (COM) mix door position hat matches the specified value?

0%

Go to Step 3

Go to Step 6

3

Compare the actual (ACT value shown on the Scan Tool ), values both hot and cold with the commanded (COM).

Are the values within the specified range?

0-5%

Go to Step 6

Go to Step 4

4

Inspect the driver air mix valve for the following conditions:

    • Binding
    • Broken components
    • Improper adjustment

Are any of these conditions present?

--

Go to Step 5

Go to Step 6

5

Repair the condition.

Is the repair complete?

--

System OK

--

6

Replace the HVAC programmer. Refer to Programmer Replacement .

Is the repair complete?

--

System OK

--