GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2005 🢒 LeSabre 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 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 determines if the instrument panel integration module (IPM) is receiving a blower speed request from the HVAC control module and commanding an output.

    3.

  3. This step tests for an open or poor connection at the blower motor control processor.

    4.

  4. This step tests for an open or poor connection at the IPM.

Step

Action

Value(s)

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 perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, perform the Recalibrate all Motors command in Instrument Panel Module (IPM) Special Functions.
  4. With a scan tool, observe the current DTC list in the IPM.

Does the scan tool display any DTCs?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

Go to Step 3

3

  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 any of the speed positions?

--

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

Go to Step 4

4

  1. Place the blower motor switch in the maximum speed position.
  2. With the scan tool, observe the Commanded Blower parameter in the Instrument Panel Module data list.

Does the scan tool indicate that the Commanded Blower parameter is near the specified value?

100%

Go to Step 6

Go to Step 5

5
  1. With the scan tool, command the blower motor ON.
  2. Observe the Commanded Blower parameter.

Does the scan tool indicate that the Commanded Blower parameter is near the specified value?

100%

Go to Step 14

Go to Step 15

6
  1. Turn OFF the ignition.
  2. Disconnect the blower motor connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the blower motor supply voltage circuit and the blower motor control circuit.
  5. Place the blower motor switch in the minimum speed position.

Does the test lamp illuminate?

--

Go to Step 12

Go to Step 7

7

Test the battery positive voltage circuit of the blower motor control processor for an open, high resistance or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 8

8

Test the ground circuit of the blower motor control processor 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 20

Go to Step 9

9

Important: Ensure that the blower motor control processor connector and the IPM connectors are connected during this step in order to avoid misdiagnosis.

  1. Measure the voltage from the blower motor speed control circuit of the IPM to a good ground.
  2. With a scan tool, command the blower motor OFF and ON.

Does the voltage measure near the specified values for each commanded state?

5.0 V OFF

1.5 V ON

Go to Step 13

Go to Step 10

10

  1. Turn OFF the ignition.
  2. Disconnect the IPM.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the blower motor speed control circuit of the IPM to a good ground.

Does the voltage measure near the specified value?

5.0 V

Go to Step 15

Go to Step 11

11

Test the blower motor speed control circuit of the IPM for an open, short to ground or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 13

12

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 20

Go to Step 16

13

Inspect for poor connections at the harness connector of the blower motor control processor. 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 20

Go to Step 17

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 20

Go to Step 18

15

Inspect for poor connections at the harness connector of the IPM. 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 20

Go to Step 19

16

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

Did you complete the replacement?

--

Go to Step 20

--

17

Replace the blower motor control processor. Refer to Blower Motor Control Processor Replacement .

Did you complete the replacement?

--

Go to Step 20

--

18

Replace the HVAC control module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 20

--

19

Replace the IPM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 20

--

20

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2