For 1990-2009 cars

Step | Action | Yes | No
--- | --- | --- | ---
A constant air rush noise is typical of high speed blower operation. Some systems and some modes may be worse than other systems and modes. If possible, inspect another similar vehicle in order to determine if the noise is typical.
1 | Did you perform the function test? | Go to Step 2 | Go to Function Test
2 | Inspect the blower electrical connections and the blower grounds. Refer to HVAC Blower Control Schematics . Is the repair complete? | Go to Function Test | Go to Step 3
3 |

1. Sit inside the vehicle.
2. Close all the doors and all of the windows.
3. Turn the ignition switch ON.
4. Set the blower speed to HIGH.
5. Set the mode control to the VENT position.
6. Set the temperature control to the coldest position.
7. Cycle through the blower speeds, through the modes, and through the temperature control positions in order to determine where the noise occurs.
8. Define the type of noise:

• | An air rush

• | A whine

• | A tick or a click

• | A squeal or a screech

• | A flutter

• | A scraping

Does the blower make a tick, a flutter, or a scraping noise, and is the noise quieter at a lower blower speed?

Go to Step 5

Go to Step 4

4 |

1. Listen to the blower for an intermittent noise or for a noise at the start-up.
2. Verify a squeal or a screech under the following conditions:

• | In a low ambient temperature

• | At a low blower speed.

Does the blower make a squeal or a screech?

Go to Step 5

Go to Step 11

5 | Feel the blower case in order to inspect for vibration of the blower motor and of the fan at each blower speed. Is the vibration excessive? | Go to Step 6 | Go to Step 7
6 |

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.

Is foreign material present?

Go to Step 8

Go to Step 7

7 |

1. Inspect the blower fan for the following conditions:

• | Wear spots

• | Cracked blades

• | A 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

8 |

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

Is the repair complete?

Go to Function Test

--

9 | Replace the blower case. Refer to Blower Motor and Fan Replacement . Is the repair complete? | Go to Function Test | --
10 | Replace the blower motor and the fan. Refer to Blower Motor and Fan Replacement . Is the repair complete? | Go to Function Test | --
11 | 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.

1. Set the blower speed to HIGH.
2. Test the hottest to the coldest temperature positions in the VENT, in the HEAT, and in the DEFROST modes.

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

Go to Step 15

Go to Step 12

12 | Listen to the blower. Is the excessive blower noise in all modes but not in all temperature positions? | Go to Step 14 | Go to Step 13
13 | The noise is mode sensitive.

1. Inspect the air ducts for obstructions, for damage, and for foreign material.
2. Inspect the vent door seals.
3. Inspect the heater door seals.
4. Inspect the defroster door seals.
5. Inspect the rubber flapper door in the center of the RECIRC door.
6. Repair the ducts, the door seals, or the door, as necessary.

Is the repair complete?

Go to Function Test

--

14 |

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

Is the repair complete?

Go to Function Test

--

15 | Inspect the heater system for obstructions or for foreign material between the blower fan and the temperature door. Repair as necessary. Is the repair complete? | Go to Function Test | --