GM Service Manual Online
For 1990-2009 cars only

Test Description

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

  1. There are 2 ignition 3 voltage circuits at the HVAC control module. Test the circuit that is not the supply voltage circuit for the blower motor switch.

Step

Action

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?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Start the engine.
  2. Place the mode switch in the VENT position.
  3. Place the blower motor switch in the maximum speed position.
  4. Place the outside air switch in the ON position.
  5. Place the recirculation switch in the ON position.

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

Go to Step 3

Go to Step 4

3

Place the mode switch in the DEFROST position.

Does the recirculation door move to the outside air position?

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

Go to Step 8

4

Does the air temperature switch operate properly?

Go to Vacuum Control System Diagnostic

Go to Step 5

5

Test the ignition 3 voltage circuit of the HVAC control assembly for an open, high resistance, or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 6

6

Test the battery positive voltage circuit of the HVAC control assembly for an open, high resistance, or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 7

7

Test the ground circuit of the HVAC control assembly 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 10

Go to Step 8

8

Inspect for poor connections at the harness connector of the HVAC control assembly. 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 assembly. Refer to Heater and Air Conditioning Control 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