GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2007 🢒 Express - AWD 🢒 HVAC 🢒 HVAC - Manual 🢒 Blower Motor Inoperative

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step tests for blower motor operation in any speed setting.

    2.

  2. This step tests for voltage at the blower motor.

    3.

  3. This step tests for a possible open in the blower motor resistor assembly or blower motor ground circuit.

    4.

  4. This step tests for output voltage from the blower motor switch.

Step

Action

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

DEFINITION: The blower motor is inoperative in all speed positions.

1

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

Go to Step 2

Go to Symptoms - HVAC Systems - Manual

2

Important: The mode switch must not be placed in the OFF position at any time during this diagnostic procedure.

  1. Turn ON the ignition, with the engine OFF.
  2. Place the mode switch to any position except OFF.
  3. Place the blower motor switch in each speed position.

Is the blower motor inoperative in all speed positions?

Go to Step 3

Go to Blower Motor Malfunction

3

Important: Do not connect the test lamp to the ground circuit in the blower motor connector.

  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 the minimum speed position.

Does the test lamp illuminate?

Go to Step 4

Go to Step 5

4

  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 the minimum speed position.

Does the test lamp illuminate?

Go to Step 11

Go to Step 9

5

  1. Turn OFF the ignition.
  2. Disconnect the blower motor resistor assembly connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Place the blower motor switch in the minimum speed position.
  5. Probe the low blower motor control circuit with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 10

Go to Step 6

6

Test all blower motor control circuits for a short to ground.

Did you find and correct the condition?

Go to Step 18

Go to Step 7

7
  1. Turn OFF the ignition.
  2. Disconnect the HVAC control assembly.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the ignition 3 voltage circuit of the HVAC control assembly with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 8

Go to Step 13

8

Test the blower motor switch supply voltage circuit for an open, a high resistance or a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 18

Go to Step 12

9

Test the ground circuit of the blower motor resistor assembly for an open or high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 18

Go to Step 10

10

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 .

Did you find and correct the condition?

Go to Step 18

Go to Step 15

11

Inspect for poor connections at the harness connector of the blower motor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 18

Go to Step 16

12

Inspect for poor connections at the harness connectors of the HVAC control assembly. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 18

Go to Step 17

13

Test the A/C request signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 18

Go to Step 14

14

Repair the ignition 3 voltage circuit of the HVAC control assembly for an open or short to ground. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 18

--

15

Replace blower motor resistor assembly. Refer to Blower Motor Resistor Assembly Replacement .

Did you complete the replacement?

Go to Step 18

--

16

Replace blower motor. Refer to Blower Motor Replacement .

Did you complete the replacement?

Go to Step 18

--

17

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

Did you complete the replacement?

Go to Step 18

--

18

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2