Schematic Reference: HVAC Schematics

DEFINITION: The blower motor is ON while the blower motor switch is in the OFF position.

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

Go to Step 2

Go to Symptoms - HVAC Systems - Manual

Important: The blower motor switch must remain in the OFF position throughout this diagnostic procedure.

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

Is the blower motor OFF?

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

Go to Step 3

1. Turn OFF the ignition.
2. Disconnect the high speed blower motor relay.
3. Turn On the ignition, with the engine OFF.

Does the blower motor continue to operate?

Go to Step 11

Go to Step 4

Probe the high blower motor control circuit of the high speed blower motor relay with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 5

Go to Step 6

Test the high blower motor control circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 14

Go to Step 10

6

Probe the blower motor supply voltage circuit (from the blower motor resistor) with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 7

Go to Step 9

Test the blower motor supply voltage circuit between the high speed blower motor relay and the blower motor resistor for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 14

Go to Step 8

Test the low, medium 1, and medium 2 blower motor control circuits for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 14

Go to Step 10

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 Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 14

Go to Step 12

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 14

Go to Step 13

Repair the short to voltage on the blower motor supply voltage circuit between the blower motor and blower motor relay. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 14

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Replace the high speed blower motor relay. Refer to Compressor Relay Replacement in Heating, Ventilation, and Air Conditioning.

Did you complete the replacement?

Go to Step 14

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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 14

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Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2