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

Schematic Reference: HVAC Schematics

Did you review the auxiliary heater and A/C operation and perform the necessary inspections?

Go to Step 2

Go to Symptoms - HVAC Systems - Manual

2

1. Turn ON the ignition, with the engine OFF.
2. Place the auxiliary heater or A/C blower motor switch in each speed position.

Does the auxiliary heater or A/C blower motor operate in each speed position?

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

Go to Step 3

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1. Disconnect the auxiliary heater or A/C blower motor connector C2.
2. Turn ON the ignition, with the engine OFF.
3. Test the auxiliary heater or A/C blower motor supply circuit with a test lamp to the auxiliary heater or A/C blower motor ground circuit. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.
4. Place the auxiliary heater or A/C blower motor switch in each speed position.

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

Go to Step 7

Go to Step 4

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Important: The auxiliary heater or A/C blower motor switch must be in the correct position for the auxiliary heater or A/C 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 heater or A/C blower motor resistor assembly.
3. Test the LO, MED and HI auxiliary heater or A/C blower motor speed control circuits with a test lamp to a known good ground. Refer to Circuit Testing in Wiring Systems.
4. Place the auxiliary heater or A/C blower motor switch in each speed position for the auxiliary heater or A/C blower motor speed control circuit being tested.

Does the test lamp illuminate in each speed position?

Go to Step 8

Go to Step 5

Test the appropriate auxiliary heater or A/C blower motor speed control circuit for an open. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 12

Go to Step 6

Inspect for poor connections at the harness connector of the appropriate auxiliary heater or A/C blower motor switch. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step  12

Go to Step  9

Inspect for poor connections at the harness connector of the appropriate auxiliary heater or A/C blower motor. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step  12

Go to Step  10

Inspect for poor connections at the harness connector of the appropriate auxiliary heater or A/C blower motor resistor assembly. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step  12

Go to Step  11

Replace the appropriate auxiliary heater or A/C blower motor switch. Refer to Heater and Air Conditioning Control Blower Switch Replacement and Heater Control Blower Switch Replacement in HVAC Systems-Manual.

Did you complete the replacement?

Go to Step 12

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Replace the appropriate auxiliary heater or A/C blower motor . Refer to Auxiliary Blower Motor Replacement or Auxiliary Air Conditioning Blower Motor Replacement in Heating, Ventilation and Air Conditioning.

Did you complete the replacement?

Go to Step 12

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Replace the appropriate auxiliary heater or A/C blower motor resistor assembly. Refer to Auxiliary Air Conditioning Blower Motor Resistor Replacement or Auxiliary Heater Blower Motor Resistor Replacement in Heating, Ventilation and Air Conditioning.

Did you complete the replacement?

Go to Step 12

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Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2