Schematic Reference : HVAC Schematics

DEFINITION: The blower motor operates in some of the speed positions.

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

Go to Step 2

Go to Symptoms - 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 supply voltage circuit of the blower motor and 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 relay to the high speed blower motor and 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 control circuit of the high speed blower motor relay with a test lamp that is connected to ground.

Does the test lamp illuminate?

Go to Step 8

Go to Step 7

Test the control circuit of the high speed blower motor relay for an open or for a high resistance. Refer to Circuit Testing and to 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 high speed blower motor relay for an open or for a high resistance. Refer to Circuit Testing and to 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 high speed blower motor relay.
3. Turn ON the ignition, with the engine OFF.
4. Probe the supply voltage circuit of the blower motor with a test lamp that is connected to ground.
5. Place the blower motor switch in the minimum speed position, in the medium 1 speed position, and in the medium 2 speed position.

Does the test lamp illuminate in each speed position?

Go to Step 13

Go to Step 10

Test the supply voltage circuit between the blower motor resistor and the relay on the high speed blower motor for an open, for a short to ground, or for a high resistance. Refer to Circuit Testing and to 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 in 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. Probe the blower motor control circuits with a test lamp that is connected to ground. Low. Medium 1. Medium 2.
5. Place the blower motor switch in the appropriate speed position for the circuit being tested.

Does the test lamp illuminate in each speed position?

Go to Step 15

Go to Step 12

Test the applicable control circuit of the blower motor resistor for an open or for a high resistance. Refer to Circuit Testing and to 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 high speed blower motor relay. 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 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 to 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 to 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 to 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 high speed 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. Refer to Blower Motor Resistor 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