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 10

1. Start the engine.
2. Place the blower motor switch in the maximum speed position.
3. Place the mode switch in the vent 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

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 5

Go to Step 11

5

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. Place the recirculation switch to the ON position.
3. Place the recirculation switch to the OFF position.

Does the measured voltage change between the specified values?

12 V ON

0 V OFF

Go to Step 9

Go to Step 6

6

Does the measured voltage remain near the specified value?

12 V

Go to Step 8

Go to Step 7

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 14

Go to Step 10

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 14

Go to Step 9

Inspect for poor connections at the harness connector of 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 14

Go to Step 12

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 14

Go to Step 13

Repair the ignition 3 voltage circuit of the vacuum control assembly for an open or high resistance. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

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Go to Step 14

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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 14

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

Did you complete the replacement?

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Go to Step 14

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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