GM Service Manual Online
For 1990-2009 cars only

Diagnostic Aids

    • The condition may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
    • Inspect the air delivery system for the following conditions:
       - An obstruction to the airflow
       - Air leaks
       - Misaligned air ducts
       - Broken or binding linkages or doors

Test Description

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

  1. To observe the recirculation actuator, lower the glove box off of the upper attachments.

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 HVAC Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Manual

2

  1. Recalibrate actuators. Refer to Actuator Recalibration .
  2. Turn ON the ignition, with the engine OFF.
  3. Perform Diagnostic Trouble Code (DTC) Displaying .
  4. Observe the Diagnostic Trouble Code (DTC) List .

Does the HVAC control module flash DTC 001?

Go to Diagnostic Trouble Code (DTC) List

Go to Step 3

3

  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 4

Go to Blower Motor Always On

4

Place the blower motor switch in each speed position.

Does the blower motor operate in any of the speed positions?

Go to Step 5

Go to Blower Motor Inoperative

5

Does the blower motor operate in each speed position?

Go to Step 6

Go to Blower Motor Malfunction

6

  1. Observe the mode actuator driveshaft.
  2. Place the mode switch in each position.

Does the mode actuator rotate?

Go to Step 7

Go to Step 8

7

  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 switch in the OFF position.

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

Go to Step 8

Go to Air Recirculation Malfunction

8

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 10

Go to Step 9

9

Replace the HVAC control module. Refer to HVAC Control Module Replacement .

Did you complete the replacement?

Go to Step 10

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10

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2