GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2007 🢒 Acadia - 2WD 🢒 HVAC 🢒 HVAC - Automatic 🢒 Air Delivery Improper

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. The test lamp should illuminate while trying to command the appropriate mode door in both directions.

  1. Two ignition circuits supply the HVAC control module. Test the ignition 1 voltage circuit.

Step

Action

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

DEFINITION: Air does not flow correctly from the air distribution outlets.

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Turn ON the ignition, with the engine OFF.
  2. Place the blower motor switch in the OFF position.

Is the blower motor OFF?

Go to Step 3

Go to Blower Motor Malfunction

3

Place the blower motor switch in each speed position.

Does the blower motor operate in any speed position?

Go to Step 4

Go to Blower Motor Malfunction

4

Does the blower motor operate in each speed position?

Go to Step 5

Go to Blower Motor Malfunction

5

Are all of the HVAC control module controls except for the blower motor inoperative?

Go to Step 15

Go to Step 6

6
  1. Place the blower motor switch in the maximum speed position.
  2. Place the mode switch in the vent position.
  3. Place the recirculation switch in the ON position.
  4. Observe the recirculation door.
  5. Place the recirculation door in the outside air position.

Does the recirculation door move from the recirculation to the outside air position?

Go to Step 7

Go to Air Recirculation Malfunction

7
  1. Place the blower motor switch in the maximum speed position.
  2. Place the mode switch in each mode position.

Does air flow sufficiently from the proper air distribution outlets for each selected mode position?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 8

8

Inspect the air delivery system for the following conditions:

    • A dirty HVAC air filter, if applicable
    • An obstruction to the airflow
    • Air leaks
    • Misaligned air ducts

Did you find and correct the condition?

Go to Step 21

Go to Step 9

9

Inspect mode door and the mode actuator for the following conditions:

    • A misaligned mode actuator Refer to Mode Actuator Replacement .
    • Broken or binding linkages or mode door
    • An obstruction that prevents the mode actuator from operating within the full range of motion
    • Missing seals to the mode door
    • Misaligned seals to the mode door

Did you find and correct the condition?

Go to Step 21

Go to Step 10

10

Test the position signal circuit of the mode actuator for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

Go to Step 21

Go to Step 11

11

Test the low reference circuit of the mode actuator for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

Go to Step 21

Go to Step 12

12

Test the 5-volt reference circuit of the mode actuator for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

Go to Step 21

Go to Step 13

13

  1. Turn OFF the ignition.
  2. Reconnect the mode actuator.
  3. Turn ON the ignition with the engine OFF.
  4. Connect a test lamp between mode door control A and mode door control B circuits of the mode actuator connector.
  5. Place the mode switch in the Defrost position.
  6. Place the mode switch in the Panel position.

Does the test lamp illuminate in both positions?

Go to Step 17

Go to Step 14

14

Test the mode door control A and mode door control B circuits of the mode actuator for an open, a high resistance, a short to ground, or a short to voltage. Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

Go to Step 21

Go to Step 18

15

Test the ignition 1 voltage circuit of the HVAC control module for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

Go to Step 21

Go to Step 16

16

Test the ground circuit of the HVAC control module for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

Go to Step 21

Go to Step 18

17

Inspect for bad connections at the harness connector of the mode actuator. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs .

Did you find and correct the condition?

Go to Step 21

Go to Step 19

18

Inspect for bad connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs .

Did you find and correct the condition?

Go to Step 21

Go to Step 20

19

Replace the mode actuator. Refer to Mode Actuator Replacement .

Did you complete the replacement?

Go to Step 21

--

20

Replace the HVAC control module. Refer to Control Module References for replacement, setup and programming.

Did you complete the replacement?

Go to Step 21

--

21

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 8