Schematic Reference: HVAC Schematics

DEFINITION: Air does not flow correctly from the air distribution outlets.

1

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. Turn ON the ignition, with the engine OFF.
2. Place the blower motor switch in the OFF position.

Is the blower motor OFF?

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Go to Step 3

Go to Blower Motor Always On

Place the blower motor switch in each speed position.

Does the blower motor operate in any speed position?

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Go to Step 4

Go to Blower Motor Inoperative

Does the blower motor operate in each speed position?

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Go to Step 5

Go to Blower Motor Malfunction

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. Alternately place the recirculation switches in the outside air and recirculation positions.

Does the air flow with sufficient volume from the proper air distribution outlets in each mode position?

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Go to Step 6

Go to Air Recirculation Malfunction

1. Place the mode switch in the vent position.
2. Place the recirculation switch in the ON position.
3. Observe the recirculation door.
4. Place the outside air switch in the ON position.

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

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

Go to Step 7

7

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. With a scan tool, command each vacuum solenoid ON and OFF.

Does each vacuum solenoid turn ON and OFF with each command?

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Go to Vacuum Control System Diagnostic

Go to Step 8

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 9

Go to Step 15

9

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

Does the voltage measure near the specified values for each commanded state?

12 V (ON)

0 volts (OFF)

Go to Step 13

Go to Step 10

10

Does the voltage remain near the specified value with each command?

12 V

Go to Step 12

Go to Step 11

Test the suspect 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 18

Go to Step 14

Test the suspect 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 18

Go to Step 14

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 18

Go to Step 16

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 18

Go to Step 17

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 18

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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 18

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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 18

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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 2