Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

DEFINITION: The auxiliary blower motor is inoperative in all speed positions.

Did you perform the Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle

1. Turn ON the ignition, with the engine OFF.
2. Place the front auxiliary blower motor switch in each speed position.

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

Go to Auxiliary Blower Motor Malfunction

Go to Step 3

1. Turn OFF the ignition.
2. Disconnect the auxiliary blower motor connector.
3. Turn ON the ignition, with the engine OFF.
4. Connect a test lamp between the auxiliary blower motor supply voltage circuit and the auxiliary blower motor speed control circuit.
5. Place the auxiliary blower motor switch in the maximum speed position.

Does the test lamp illuminate?

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Go to Step 10

Go to Step 4

Test the battery positive voltage circuit of the auxiliary blower motor for an open, high resistance or short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

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Go to Step 16

Go to Step 5

Test the blower motor speed control circuit of the auxiliary blower motor for an open or high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

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Go to Step 16

Go to Step 6

Important: Ensure that the auxiliary blower motor resistor connector and the HVAC control module connectors are connected during this step in order to avoid misdiagnosis.

1. Place the auxiliary blower motor switch in any position except OFF.
2. Backprobe and measure the voltage from the auxiliary blower motor speed control circuit of the HVAC control module to a good ground.

Does the voltage measure near the specified value?

4-8 V

Go to Step 11

Go to Step 7

1. Turn OFF the ignition.
2. Disconnect the HVAC control module.
3. Turn ON the ignition, with the engine OFF.
4. Measure the voltage from the auxiliary blower motor speed signal circuit of the HVAC control module to a good ground.

Does the voltage measure near the specified value?

4-6 V

Go to Step 9

Go to Step 8

Test the auxiliary blower motor speed control circuit of the HVAC control module for an open or a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

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Go to Step 16

Go to Step 11

Test the auxiliary blower motor speed control circuit of the HVAC control module for a short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

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Go to Step 16

Go to Step 12

Inspect for poor connections at the harness connector of the auxiliary blower motor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

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Go to Step 16

Go to Step 13

Inspect for poor connections at the harness connector of the auxiliary blower motor resistor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

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Go to Step 16

Go to Step 14

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 .

Did you find and correct the condition?

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Go to Step 16

Go to Step 15

Replace the auxiliary blower motor. Refer to Auxiliary Blower Motor Replacement .

Did you complete the replacement?

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Go to Step 16

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Replace the auxiliary blower motor resistor. Refer to Auxiliary Blower Motor Resistor Replacement .

Did you complete the replacement?

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Go to Step 16

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Replace the HVAC control module. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

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Go to Step 16

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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