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For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2006 🢒 Envoy - 2WD 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 Air Delivery Improper - Auxiliary

Step

Action

Values

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

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

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2
  1. Turn ON the ignition, with the engine OFF.
  2. Place the blower motor switch in the maximum position.
  3. Place the mode switch in the defrost position.
  4. With a scan tool, observe the Rear HVAC parameter in the Heating and Air Conditioning data list.

Does the scan tool indicate that the Rear HVAC parameter displays Disabled?

--

Go to Step 3

Go to Step 22

3
  1. Place the front mode switch in the floor position.
  2. With a scan tool, observe the Rear HVAC parameter in the Heating and Air Conditioning data list.

Does the scan tool indicate that the Rear HVAC parameter displays Enabled?

--

Go to Step 4

Go to Step 22

4
  1. Turn ON the headlamps.
  2. Place the instrument panel dimmer switch in the brightest position.
  3. Turn ON the auxiliary HVAC control module.

Does the power indicator of the auxiliary HVAC control module illuminate?

--

Go to Step 5

Go to Step 7

5

Place the auxiliary mode switch in each position.

Is the airflow sufficient from the correct auxiliary outlets in each mode?

--

Go to Step 6

Go to Step 11

6

Place the front mode switch in the defrost position.

Is there airflow from the auxiliary outlets?

--

Go to Step 15

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

7
  1. Turn OFF the ignition.
  2. Disconnect the auxiliary HVAC control module.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the ignition 3 voltage circuit of the auxiliary HVAC control module with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

--

Go to Step 8

Go to Step 23

8

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

Did you find and correct the condition?

--

Go to Step 28

Go to Step 9

9

Probe the auxiliary HVAC enable control circuit of the auxiliary HVAC control module with a test lamp that is connected to battery positive voltage.

Does the test lamp illuminate?

--

Go to Step 10

Go to Step 21

10

Test the auxiliary HVAC enable control circuit of the auxiliary HVAC control module for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 28

Go to Step 22

11
  1. Turn OFF the ignition.
  2. Disconnect the auxiliary mode actuator.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the ignition 3 voltage circuit of the auxiliary mode actuator with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

--

Go to Step 12

Go to Step 24

12
  1. Measure the voltage from the auxiliary mode door control circuit of the auxiliary mode actuator to a good ground.
  2. Place the auxiliary mode switch in each position.

Does the voltage measure near the specified values?

3-5 V FLOOR

7-9 V BI-LEVEL

11-13 V PANEL

Go to Step 13

Go to Step 14

13

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

Did you find and correct the condition?

--

Go to Step 28

Go to Step 19

14

Test the auxiliary mode door control circuit of the auxiliary mode actuator for following:

    • an open
    • a high resistance
    • a short to ground
    • a short to voltage

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 28

Go to Step 21

15

Does the power indicator illuminate on the auxiliary HVAC control module?

--

Go to Step 16

Go to Step 18

16
  1. Turn OFF the ignition.
  2. Disconnect the auxiliary HVAC control module.
  3. Turn ON the ignition, with the engine OFF.
  4. Place the front mode switch in the defrost position.
  5. Measure the voltage from the auxiliary HVAC enable control circuit to battery positive voltage.

Does the voltage measure near the specified value?

B+

Go to Step 21

Go to Step 17

17

Test the auxiliary HVAC enable control circuit of the auxiliary HVAC control module for an open or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 28

Go to Step 22

18
  1. Measure the voltage from the auxiliary mode door control circuit of the auxiliary mode actuator to a good ground.
  2. Turn OFF the auxiliary HVAC control module.

Does the voltage measure near the specified value?

0 V

Go to Step 19

Go to Step 21

19

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

    • Misaligned auxiliary mode actuator
    • Broken or binding linkages or auxiliary mode door
    • Obstruction that prevents the recirculation actuator from operating within its full range of motion
    • Missing seals to the auxiliary mode door
    • Misaligned seals to the auxiliary mode door

Did you find and correct the condition?

--

Go to Step 28

Go to Step 20

20

Inspect for poor connections at the harness connector of the auxiliary mode actuator. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 28

Go to Step 25

21

Inspect for poor connections at the harness connector of the auxiliary HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 28

Go to Step 26

22

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

Did you find and correct the condition?

--

Go to Step 28

Go to Step 27

23

Repair the ignition 3 voltage circuit of the auxiliary HVAC control module. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 28

--

24

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

Did you complete the repair?

--

Go to Step 28

--

25

Replace the auxiliary mode actuator. Refer to Auxiliary Mode Valve Actuator Replacement .

Did you complete the replacement?

--

Go to Step 28

--

26

Replace the auxiliary HVAC control module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 28

--

27

Replace the HVAC control module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 28

--

28

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2