Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

DEFINITION: The auxiliary blower motor operates in at least one, but not all, speed positions.

Did you review the auxiliary HVAC operation and perform the necessary inspections?

Go to Step 2

Go to Symptoms - HVAC Systems - Manual

2

Important: The rear auxiliary HVAC control assembly will only function if the front auxiliary blower motor switch is placed in the Aux.position.

1. Turn ON the ignition, with the engine OFF.
2. Operate the auxiliary blower motor in each speed position from both the front and rear auxiliary HVAC control assemblies.

Does the auxiliary blower motor operate correctly in each speed position from both the front and rear auxiliary HVAC control assemblies?

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

Go to Step 3

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1. Set the front auxiliary blower motor switch to enable the rear auxiliary HVAC control assembly.
2. Place the rear auxiliary blower motor switch in each speed position.

Does the auxiliary blower motor operate in each speed position?

Go to Step 8

Go to Step 4

4

Place the front auxiliary blower motor switch in each speed position.

Does the auxiliary blower motor operate in each speed position?

Go to Step 9

Go to Step 5

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 circuit and the auxiliary blower motor ground circuit.
5. Place the auxiliary blower motor switch in each speed position.

Does the test lamp illuminate and change intensity in each speed position?

Go to Step 17

Go to Step 6

Important: The auxiliary blower motor switch must be in the correct position for the auxiliary blower motor speed control circuit being tested. Failure to do this will result in a misdiagnosis.

1. Turn OFF the ignition.
2. Disconnect the auxiliary blower motor resistor assembly connector C1.
3. Probe each auxiliary blower motor speed control circuit with a test lamp that is connected to battery positive voltage.
4. Place the front auxiliary blower motor switch in each speed position for the auxiliary blower motor speed control circuit being tested.

Does the test lamp illuminate in each position?

Go to Step 18

Go to Step 7

Test the appropriate auxiliary blower motor speed control circuit for an open or high resistance between the auxiliary blower motor resistor assembly and the rear auxiliary HVAC control assembly. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 24

Go to Step 14

Test each auxiliary blower motor speed control circuit for an open or high resistance between the front auxiliary HVAC control assembly and the rear auxiliary HVAC control assembly. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 24

Go to Step 15

1. Turn OFF the ignition.
2. Disconnect the front auxiliary HVAC control assembly.
3. Turn ON the ignition, with the engine OFF.
4. Place the rear auxiliary blower motor switch in the maximum speed position.
5. Connect a 3 amp fused jumper wire between the rear auxiliary enable control circuit and the front auxiliary HVAC control assembly ground circuit.

Does the auxiliary blower motor operate?

Go to Step 15

Go to Step 10

Is the vehicle equipped with auxiliary heat and a/c?

Go to Step 12

Go to Step 11

Test the rear auxiliary enable control circuit 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 24

Go to Step 14

1. Turn OFF the ignition.
2. Disconnect the auxiliary HVAC control processor.
3. Turn ON the ignition, with the engine OFF.
4. Connect a 3 amp fused jumper wire between auxiliary blower motor control circuit and the auxiliary HVAC control processor ground circuit.

Does the auxiliary blower motor operate?

Go to Step 16

Go to Step 13

Test auxiliary blower motor control circuit 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 24

Go to Step 14

Inspect for poor connections at the harness connector of the rear auxiliary 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 24

Go to Step 19

Inspect for poor connections at the harness connector of the front auxiliary 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 24

Go to Step 22

Inspect for poor connections at the harness connector of the auxiliary HVAC control processor. 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 24

Go to Step 23

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 in Wiring Systems.

Did you find and correct the condition?

Go to Step 24

Go to Step 20

Inspect for poor connections at the harness connectors of the auxiliary blower motor resistor 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 24

Go to Step 21

Replace the rear auxiliary HVAC control assembly. Refer to Auxiliary Heater and Air Conditioning Control Replacement - Rear .

Did you complete the replacement?

Go to Step 24

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Replace the auxiliary blower motor. Refer to Auxiliary Blower Motor Replacement in Heating, Ventilation and Air Conditioning.

Did you complete the replacement?

Go to Step 24

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Replace the auxiliary blower motor resistor assembly. Refer to Auxiliary Blower Motor Resistor Replacement in Heating, Ventilation and Air Conditioning.

Did you complete the replacement?

Go to Step 24

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Replace the front auxiliary HVAC control assembly. Refer to Auxiliary Heater and Air Conditioning Control Replacement - Front .

Did you complete the replacement?

Go to Step 24

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Replace the auxiliary HVAC control processor. Refer to Auxiliary HVAC Control Processor Replacement .

Did you complete the replacement?

Go to Step 24

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Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2