GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2001 🢒 Firebird 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 Noise Diagnosis - Blower Motor

Step

Action

Value(s)

Yes

No

DEFINITION: Noise originating from the blower motor and/or the air delivery system. No loss of battery or ground is occurring in the blower motor circuit. The blower motor resistor and the blower motor are not exhibiting any intermittent internal shorts. For electrical diagnosis of the blower motor circuit, refer to Blower Motor Inoperative in HVAC Systems - Manual.

1

Were you sent here from A Diagnostic System Check?

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Go to Step 2

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2
  1. Sit inside the vehicle.
  2. Close the vehicle doors and windows.
  3. Turn the ignition switch to ON; engine OFF.
  4. Turn the blower switch to position 5 (high).
  5. Set the temperature control to full cold.
  6. Set the mode control to UPPER (I/P outlets).
  7. Cycle through all the blower motor speeds, modes (including outside air and recirc) and temperature control positions to determine where noise occurs and where noise does not occur.
  8. Attempt to define the type of noise:
    9. • Scrape, pop
    • Tick/click, chirping, groaning, scraping
    • Air rush/whistle

Is a scrape or pop noise evident when selecting modes or temperature settings (moving a mode or temperature valve)?

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Go to Step 12

Go to Step 3

3

Is a tick/click, chirping, groaning or scraping noise present (constantly but decreases as blower motor speed is decreased, or only at start-up/intermttent) in all modes?

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Go to Step 6

Go to Step 4

4

Is an air rush/whistle noise evident in all modes but not all temperature settings?

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Go to Step 13

Go to Step 5

5

Is an air rush/whistle noise evident only in defrost or lower mode?

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Go to Step 14

Go to Step 15

6

Check for blower motor and impeller excess vibration at each blower motor speed by feeling the blower case.

Is excessive vibration present?

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Go to Step 7

Go to Step 9

7
  1. Remove the blower motor (w/impeller).

    2. Refer to Blower Motor and Fan Replacement .

  2. Examine the blower motor impeller for the following conditions:
    3. • Deposits of foreign material
    • Wear spots
    • Cracked blades
    • Cracked hub
    • Loose impeller retainer
    • Improper impeller alignment

Does the blower motor impeller exhibit any of these abnormal conditions?

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Go to Step 8

Go to Step 9

8
  1. Repair or replace the blower motor impeller.
  2. Install the blower motor and impeller.

    3. Refer to Blower Motor and Fan Replacement .

Is the action complete?

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Go to Step 16

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9
  1. Remove the blower motor (w/impeller).

    2. Refer to Blower Motor and Fan Replacement .

  2. Check for the presence of foreign material at the opening of the blower intake.

Was foreign material found?

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Go to Step 11

Go to Step 10

10
  1. Replace the blower motor.
  2. Install the blower motor and impeller.

    3. Refer to Blower Motor and Fan Replacement .

Is the repair complete?

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Go to Step 17

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11
  1. Remove the foreign material from the blower case.
  2. Repair as necessary.

Is the action complete?

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Go to Step 17

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12
  1. Remove the instrument panel (IP) upper trim pad.

    2. Refer to Instrument Panel Upper Trim Pad Replacement in Instrument Panel, Gauges and Console.

  2. Check the defroster, mode, air inlet and temperature valve function.
  3. Repair or replace as necessary.

Is the action complete?

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Go to Step 17

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13
  1. Remove the IP upper trim pad.

    2. Refer to Instrument Panel Upper Trim Pad Replacement in Instrument Panel, Gauges and Console.

  2. Check the temperature valve seals.
  3. Repair or replace as necessary.

Is the action complete?

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Go to Step 17

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14
  1. Remove the IP upper trim pad.

    2. Refer to Instrument Panel Upper Trim Pad Replacement in Instrument Panel, Gauges and Console.

  2. Check the ducts for obstructions or foreign materials.
  3. Remove any obstructions or foreign material found.
  4. Check the defroster valve function.
  5. Repair or replace as necessary.

Is the action complete?

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Go to Step 17

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15
  1. Remove the IP upper trim pad.

    2. Refer to Instrument Panel Upper Trim Pad Replacement in Instrument Panel, Gauges and Console.

  2. Check the ducts for obstructions or foreign materials.
  3. Remove any obstructions or foreign material found.
  4. Check the defroster valve seals.
  5. Repair or replace as necessary.

Is the action complete?

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Go to Step 17

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16
  1. Turn OFF the ignition switch.
  2. Reconnect or install any connectors or components which were disconnected or removed.
  3. Recheck for the presence of blower motor/air delivery system noise.

Is the noise still present?

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Go to Step 10

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17
  1. Turn OFF the ignition switch.
  2. Reconnect or install any connectors or components which were disconnected or removed.
  3. Recheck for the presence of blower motor/air delivery system noise.

Is the noise still present?

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Go to Step 2

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