Important: A constant air rush noise is typical of high speed blower operation. Some systems and modes may be worse than others. If possible, inspect another similar vehicle in order to determine whether the noise is typical of the system as designed or excessive.

Was the Function Test performed?

Go to Step 2

Go to Function Test

Test the blower electrical connections and grounds. Refer to HVAC Schematics .

Is the repair complete?

Go to Function Test

Go to Step 3

1. Sit inside the vehicle.
2. Close all of the doors and windows.
3. Turn the ignition switch to 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 of the blower speeds, modes, and temperature control positions in order to determine where the noise occurs and where it does not occur.
8. Try to define the type of noise: air rush, whine, tick/click, squeal/screech, flutter, rumble or scraping noise.

Is the blower making a constant whine, tick/click, flutter or scraping noise that lessens with a lower blower speed?

Go to Step 5

Go to Step 4

Listen to the blower again.

Is the blower making a squeal/screech noise at cold ambient temperatures or low blower speeds at start-up only and/or intermittently?

Go to Step 5

Go to Step 11

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 7

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.

Does any foreign material exist?

Go to Step 8

Go to Step 7

1. Inspect the blower fan for the following conditions:

•	Wear spots

•	Cracked blades

•	Cracked hub

•	A loose fan retainer

2. Inspect the fan alignment.
3. Inspect the blower case for wear spots.

Is the blower case worn or damaged?

Go to Step 9

Go to Step 10

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

Is the repair complete?

Go to Function Test

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Replace the blower case. Refer to Blower Motor and Fan Replacement .

Is the repair complete?

Go to Function Test

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

Is the repair complete?

Go to Function Test

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1. The noise is constant at high blower speeds with some door combinations but can be eliminated at lower blower speeds or with other door combinations
2. Set the blower speed to HIGH.
3. Test the hottest to coldest temperature positions in the VENT, HEAT, and DEFROSTER modes.

Is the excessive blower noise in all modes and all temperature positions?

Go to Step 15

Go to Step 12

Listen to the blower again.

Is the excessive blower noise in every mode but not in every temperature position?

Go to Step 14

Go to Step 13

1. The noise is mode sensitive.
2. Inspect the air ducts for obstructions, damage and foreign material.
3. Inspect the vent door seals.
4. Inspect the heater door seals.
5. Inspect the defroster door seals.
6. Repair as necessary.

Is the repair complete?

Go to Function Test

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

Is the repair complete?

Go to Function Test

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

Is the repair complete?

Go to Function Test

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