Schematic Reference: HVAC Schematics

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

Did you perform the HVAC Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Manual

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

Does the blower motor operate in each speed position?

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

Go to Step 3

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

When the blower motor is in each speed position, does the test lamp illuminate?

Go to Step 7

Go to Step 4

1. Turn OFF the ignition.
2. Disconnect the blower motor resistor assembly.
3. Turn ON the ignition, with the engine OFF.
4. Connect a test lamp between the battery positive voltage circuit of the blower motor resistor assembly and a good ground.

Does the test lamp illuminate?

Go to Step 5

Go to Step 12

5

Important: Place the blower motor switch in the correct speed position for the control circuit that you are testing.

1. Probe each blower motor control circuit with a test lamp that is connected to a good ground.
2. Place the blower motor switch in the appropriate speed position for the blower motor control circuit being tested.

Does the test lamp illuminate in each speed position?

Go to Step 10

Go to Step 6

6

Test the appropriate 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 16

Go to Step 11

1. Connect a test lamp between the blower motor supply voltage circuit and the blower motor ground circuit.
2. Place the blower motor switch in each speed position.

Does the test lamp illuminate in each speed position?

Go to Step 9

Go to Step 8

Test the ground circuit of the blower motor resistor assembly for a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 16

Go to Step 10

Inspect for poor connections at the harness connector of the 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 16

Go to Step 13

Inspect for poor connections at the harness connectors of the 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 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 in Wiring Systems.

Did you find and correct the condition?

Go to Step 16

Go to Step 15

Repair the battery positive voltage circuit of the blower motor resistor assembly. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 16

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

Did you complete the replacement?

Go to Step 16

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

Did you complete the replacement?

Go to Step 16

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

Did you complete the replacement?

Go to Step 16

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Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3