GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2006 🢒 Rendezvous - FWD 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 Air Delivery Improper

Test Description

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

  1. The measured voltage should be near the specified values for each mode position.

  1. Two ignition 3 voltage circuits supply the HVAC control module. Test the ignition 3 voltage circuit that does not supply the blower motor switch.

Step

Action

Value

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 Always On

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 Inoperative

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 14

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 outside air switch in the ON 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 23

Go to Step 9

9

Inspect the 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 23

Go to Step 10

10
  1. Turn OFF the ignition.
  2. Disconnect the mode actuator.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the ignition 3 voltage circuit of the mode actuator with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

--

Go to Step 11

Go to Step 20

11

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

Did you find and correct the condition?

--

Go to Step 23

Go to Step 12

12

  1. Turn OFF the ignition.
  2. Reconnect the mode actuator.
  3. Turn ON the ignition with the engine OFF.
  4. Measure the voltage from the mode door control circuit of the mode actuator to a good ground.
  5. Observe the control circuit voltage of the mode door .
  6. Place the mode switch in each mode position.

Does the voltage measure near the specified values for each mode position?

Vent: 0.2V, Bi-Level: 3.1V, Floor: 5.0V Mix-Blend: 8.9V, Defrost: 11.8V

Go to Step 18

Go to Step 13

13

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

Did you find and correct the condition?

---

Go to Step 23

Go to Step 19

14

Test the ignition 3 voltage circuit of the HVAC control module for an open or for a high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 23

Go to Step 15

15

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

Did you find and correct the condition?

--

Go to Step 23

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 Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 23

Go to Step 17

17

Test the off blower motor control circuit of the HVAC control module for a short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 23

Go to Step 19

18

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

Did you find and correct the condition?

--

Go to Step 23

Go to Step 21

19

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

Did you find and correct the condition?

--

Go to Step 23

Go to Step 22

20

Repair the ignition 3 voltage circuit of the mode actuator. Refer to Wiring Repairs .

Did you complete the repair?

--

Go to Step 23

--

21

Replace the mode actuator. Refer to Mode Actuator Replacement .

Did you complete the replacement?

--

Go to Step 23

--

22

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

Did you complete the replacement?

--

Go to Step 23

--

23

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 8