GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2002 🢒 Venture Ext. 🢒 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. The HVAC control module is supplied by two ignition 3 voltage circuits. 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 HVAC Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Manual

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 at all?

--

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

Except for the blower motor speed, are all of the functions of the HVAC control module 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 switches in the recirculation position and in the outside air position.

Does the recirculation door move to the correct position for each selection?

--

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 position.

Is the air flow sufficient from the correct outlets in each mode?

--

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

Go to Step 8

8

Inspect the air distribution system for the following conditions:

    • A dirty HVAC air filter, if applicable
    • An obstruction to the air flow
    • 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 its 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 high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 12

12

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

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

Vent 0.2V, Bi-Level 3.0V, Floor 6.0V, Mix-Blend 9.0V, Defrost 12.0V

Go to Step 18

Go to Step 13

13

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

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 high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

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 high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

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 high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

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 in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 19

18

Inspect for poor connections at the harness connector of the 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 23

Go to Step 21

19

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 23

Go to Step 22

20

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

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 HVAC Control Module Replacement .

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