Schematic Reference: HVAC Schematics

DEFINITION: Air recirculation is inoperative or is always ON.

Did you perform the HVAC Diagnostic System Check?

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Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Automatic

1. Install a scan tool.
2. With a scan tool, observe the Outside Air Button parameter in the Heating and Air Conditioning data list.
3. Activate the outside air switch.
4. With a scan tool, observe the Recirculate Button parameter in the Heating and Air Conditioning data list.
5. Activate the recirculation switch.

Does the scan tool indicate that both the Outside Air Button and Recirculate Button parameters change state?

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Go to Step 3

Go to Step 11

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

Does the recirculation door operate properly?

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

Go to Step 4

4

With a scan tool, command the recirculation mode valve solenoid (Sol. 4-Air Inlet) ON and OFF.

Does the recirculation mode valve solenoid turn ON and OFF?

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Go to Vacuum Control System Diagnostic

Go to Step 5

5

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

Does the test lamp illuminate?

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Go to Step 6

Go to Step 12

6

1. Measure the voltage between the ignition 3 voltage circuit of the vacuum control assembly and the recirculation mode valve solenoid control circuit of the vacuum control assembly.
2. With a scan tool, command the recirculation mode valve solenoid ON and OFF.

Does the measured voltage change between the specified values?

0-12 V

Go to Step 10

Go to Step 7

7

Does the measured voltage remain near the specified value?

12 V

Go to Step 9

Go to Step 8

Test the recirculation mode valve solenoid control circuit of the vacuum control assembly for a short to voltage or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

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Go to Step 15

Go to Step 11

Test the recirculation mode valve solenoid control circuit of the vacuum control assembly for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

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Go to Step 15

Go to Step 10

Inspect for poor connections at the vacuum control assembly. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

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Go to Step 15

Go to Step 13

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?

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Go to Step 15

Go to Step 14

Repair the ignition 3 voltage circuit of the vacuum control assembly. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

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Go to Step 15

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Replace the vacuum control assembly. Refer to Vacuum Control Assembly Replacement .

Did you complete the replacement?

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Go to Step 15

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Important: Perform the recalibration procedure for the HVAC control module.

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

Did you complete the replacement?

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Go to Step 15

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Operate the system in order to verify the repair.

Did you correct the condition?

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System OK

Go to Step 4