For 1990-2009 cars

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
A constant air rush is typical of high speed blower operation. Some systems and modes may be worse than others. Inspect another similar vehicle in order to determine whether the noise is typical or excessive.
1 | Inspect the blower electrical connections and grounds. Refer to HVAC Blower Control 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 noise 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 Functional Check Is the repair complete? | -- | System OK | --

### Compressor

Resonant compressor noises are not a cause for alarm. Irregular noises or rattles may indicate broken parts or excessive wear.

An excessive noise coming from inside the compressor could be a defect in 1 of the following components:

• | The piston shoe

• | The bearing

• | The cylinder

• | The shaft

If any of these parts are defective, replace the compressor assembly. Refer to Air Conditioning Compressor Replacement .

An excessive noise coming from the magnetic clutch face area can relate to a magnetic clutch or a defective bearing. Replace the magnetic clutch if the noise comes from the clutch. If the noise is not coming from the clutch, replace the compressor assembly. Refer to Air Conditioning Compressor Replacement .