DEFINITION: A constant air rush noise is typical of all heater systems. Some systems may be louder than others. If possible, inspect a similar vehicle in order to determine whether the noise is typical or excessive.

Did you perform the Function Test?

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Go to Step 2

Go to Function Test

1. Inspect all of the electrical connections and the grounds for proper connections.
2. If a connection is doubtful, use a voltmeter in order to test for constant voltage at the blower motor.

Is the repair complete?

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Go to Step 3

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1. Sit in the vehicle with the doors and windows closed.
2. With the ignition switch in the ON position and the engine off, start the blower motor on the HI mode.
3. Select full COLD on the temperature rotary knob.
4. Cycle through the blower motor speeds, modes and temperature rotary knob positions in order to find where the noise occurs.
5. Define the noise as one of the following types:

•	An air rush

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A whine

•	A tick/click

•	A squeal/screech

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A flutter

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A rumble

•

A scrape

6. If possible, compare the noise with another vehicle of the same model in order to determine if the noise is typical.

Is the noise typically a flutter or a rumble that is constant at high blower motor speeds in certain modes, but can be eliminated at lower blower motor speeds?

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Go to Step 4

Go to Step 6

With the blower motor on HI, inspect the full HOT to the full COLD temperature positions in all modes.

Is the noise audible in all modes and in all temperature positions?

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Go to Step 5

Go to Step 8

1. Inspect the system for obstructions or foreign materials between the fan and the temperature door.
2. Remove, repair, or replace the fan and the temperature door as necessary.
3. Recheck the system for the noise.

Is the noise audible?

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Go to Step 3

Go to Function Test

Feel the blower motor armature in order to check for vibration of the motor and the fan at each blower motor speed.

Is the vibration excessive?

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Go to Step 7

Go to Step 10

1. Examine the blower motor fan for wear spots, cracked blades, or a cracked hub.
2. Examine the blower motor case for wear spots.
3. Repair or replace parts as necessary.
4. Recheck the system for the blower motor noise.

Did you find and correct the condition?

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Go to Function Test

Go to Step 11

Is the noise audible in all modes, but not audible in all temperature positions?

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Go to Step 9

Go to Step 12

1. Inspect the temperature door seals.
2. Repair or replace the temperature door seals as necessary.
3. Recheck the system for the noise.

Is the repair complete?

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Go to Function Test

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1. Remove the blower motor and fan assembly. Refer to Blower Motor and Fan Replacement .
2. Inspect for foreign material at the orifice of the blower inlet.
3. Repair or replace the blower motor and fan assembly as necessary.
4. Recheck the system for the noise.

Did you find and correct the condition?

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Go to Function Test

Go to Step 7

1. Replace the blower motor and fan assembly. Refer to Blower Motor and Fan Replacement .
2. Recheck the system for the noise.

Did you find and correct the condition?

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Go to Function Test

Go to Step 13

1. Inspect the ducts of the noisy modes for obstructions.
2. Remove any obstructions.
3. Inspect the seals of the suspected mode doors.
4. Repair or replace the doors as necessary.
5. Recheck the system for the noise.

Is the repair complete?

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Go to Function Test

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Is the noise a click/tick or a whine?

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Go to Step 14

Go to Step 4

Replace the blower motor and fan assembly with a second new blower motor and fan assembly.

Did you find and correct the condition?

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Go to Function Test

Go to Step 15

Reinstall the original blower motor and fan assembly.

Is the repair complete?

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Go to Function Test

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