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 mode switch in the vent position.
3. Place the blower motor switch in each speed position.

Does the blower motor operate at the desired speed 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 of the blower motor and a good ground.
5. Place the blower motor switch in each speed position.

Does the test lamp illuminate in each speed position?

Go to Step 14

Go to Step 4

Does the test lamp illuminate in the maximum speed position?

Go to Step 9

Go to Step 5

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

Does the test lamp illuminate?

Go to Step 6

Go to Step 17

1. Place the blower motor switch in the maximum speed position.
2. Probe the high blower motor control circuit of the blower motor relay with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 8

Go to Step 7

Test the high blower motor control circuit of the blower motor relay 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 22

Go to Step 16

Test the ground circuit of the blower motor relay 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 22

Go to Step 13

9

1. Turn OFF the ignition.
2. Disconnect the blower motor relay.
3. Turn ON the ignition, with the engine OFF.
4. Probe the blower motor supply voltage circuit with a test lamp that is connected to a good ground.
5. Place the blower motor switch in the low, medium 1, medium 2, and medium 3 speed positions.

Does the test lamp illuminate in each speed position?

Go to Step 13

Go to Step 10

Test the blower motor supply voltage circuit between the blower motor resistor and blower motor relay for an open, short to ground, or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 22

Go to Step 11

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

1. Turn OFF the ignition.
2. Disconnect the blower motor resistor.
3. Turn ON the ignition, with the engine OFF.
4. Place the blower motor switch in the appropriate speed position for the circuit being tested.
5. Probe the low, medium 1, medium 2, and medium 3 blower motor control circuits with a test lamp that is connected to good ground.

Does the test lamp illuminate in each speed position?

Go to Step 15

Go to Step 12

Test the applicable blower motor control circuit of the blower motor resistor 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 22

Go to Step 16

Inspect for poor connections at the harness connector of the blower motor relay. 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 22

Go to Step 18

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 22

Go to Step 19

Inspect for poor connections at the harness connector of the blower motor resistor. 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 22

Go to Step 20

Inspect for poor connections at the harness connector of the 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 22

Go to Step 21

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

Did you complete the repair?

Go to Step 22

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Replace the blower motor relay.

Did you complete the replacement?

Go to Step 22

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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 22

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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 22

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Replace the HVAC control assembly. Refer to Heater and Air Conditioning Control Replacement .

Did you complete the replacement?

Go to Step 22

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Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3