GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 1998 🢒 Firefly (Canada) 🢒 HVAC 🢒 Heating, Ventilation and Air Conditioning 🢒 Noise Diagnosis

Step

Action

Value(s)

Yes

No

1

Inspect the blower electrical connections and grounds. Refer to Heater Blower Controls Schematics .

Is the action complete?

--

Go to Step 2

--

2
  1. Sit inside the vehicle.
  2. Close all the doors and the windows.
  3. Turn the ignition switch ON.
  4. Set the blower speed to HI.
  5. Set the mode to VENT.
  6. Set the temperature control to full COLD.
  7. Cycle through all the blower speeds, modes, and temperature control positions in order to determine where the noise occurs and where it does not occur.

Does the blower make a constant whine, tick/click, flutter or scrapping noise that lessens with a lower blower speed?

--

Go to Step 4

Go to Step 3

3

Listen to the blower.

Does the blower make a squeal or screech at the start-up only or sometimes intermittent?

--

Go to Step 4

Go to Step 7

4

Inspect for blower motor and fan vibration at each blower speed by feeling the blower case.

Is the vibration excessive?

--

Go to Step 6

Go to Step 5

5
  1. Remove the blower from the blower case. Refer to Blower Motor and Fan Replacement .
  2. Inspect for foreign material at the opening of the blower intake.

Was foreign material found?

--

Go to Step 10

Go to Step 6

6
  1. Inspect the blower for wear spots, cracked blades, or hub, loose fan retainer, and fan alignment.
  2. Inspect the blower case for wear spots.

Was any wear found?

--

Go to Step 11

Go to Step 12

7
  1. Set the blower speed to HI.
  2. Test the full HOT to the full COLD temperature positions in VENT, HEAT, and DEFROSTER modes.

Is the excessive blower noise in the VENT mode only?

--

Go to Step 13

Go to Step 8

8

Listen to the blower.

Is the excessive blower noise in the HEAT and/or DEFROST modes only?

--

Go to Step 14

Go to Step 9

9

Listen to the blower.

Is the excessive blower noise in all modes but not in all temperature positions?

--

Go to Step 15

Go to Step 16

10

Remove the foreign material from the blower assembly. Repair as necessary.

Is the repair complete?

--

Go to Step 17

--

11

Repair the blower fan and/or the blower case as necessary.

Is the repair complete?

--

Go to Step 17

--

12

Replace the blower motor and the fan. Refer to Blower Motor and Fan Replacement .

Is the repair complete?

--

Go to Step 17

--

13
  1. Inspect the air ducts for obstructions and foreign material.
  2. Inspect the vent door seals.
  3. Inspect the rubber flapper door in the center of the RECIRC door.
  4. Repair as necessary.

Is the repair complete?

--

Go to Step 17

--

14
  1. Inspect the air ducts for obstructions and foreign material.
  2. Inspect the heater and/or defroster seals.
  3. Repair as necessary.

Is the repair complete?

--

Go to Step 17

--

15
  1. Inspect the temperature door seals.
  2. Repair the seals as necessary.

Is the repair complete?

--

Go to Step 17

--

16

Inspect the heater system for obstructions or foreign material between the blower fan and the temperature door. Repair as necessary.

Is the repair complete?

--

Go to Step 17

--

17

Perform the functional test. Refer to Function Test .

Is the action complete?

--

System OK

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