GM Service Manual Online
For 1990-2009 cars only

Test Description

The number below refers to the step number on the diagnostic table.

  1. The HVAC control module is supplied by 2 ignition 3 voltage circuits. Test the ignition 3 voltage circuit that does not supply the blower motor switch.

Step

Action

Values

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

DEFINITION: Air recirculation is inoperative or is always ON.

1

Did you perform the Diagnostic System Check - Vehicle?

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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 speed position.
  3. Place the mode switch in the vent position.
  4. 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 Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

Except for the blower motor speed, are all of the functions of the HVAC control module inoperative?

--

Go to Step 9

Go to Step 4

4

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

Does the test lamp illuminate?

--

Go to Step 5

Go to Step 15

5

Test the ground circuit of the recirculation 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 18

Go to Step 6

6

  1. Measure the voltage from the recirculation door control circuit of the recirculation actuator to a good ground.
  2. Place the recirculation switches in the outside air position and the recirculation position.

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

0.25 V  Outside Air

10-12 V  Recirc.

Go to Step 8

Go to Step 7

7

Test the recirculation door control circuit of the recirculation 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 18

Go to Step 14

8

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

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

Did you find and correct the condition?

--

Go to Step 18

Go to Step 13

9

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 18

Go to Step 10

10

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 18

Go to Step 11

11

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 18

Go to Step 12

12

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 18

Go to Step 14

13

Inspect for poor connections at the harness connector of the recirculation 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 18

Go to Step 16

14

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 18

Go to Step 17

15

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

Did you complete the repair?

--

Go to Step 18

--

16

Replace the recirculation actuator. Refer to Recirculation Actuator Replacement .

Did you complete the replacement?

--

Go to Step 18

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17

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 18

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18

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 3