For 1990-2009 cars

Step | Action | Yes | No
--- | --- | --- | ---
DEFINITION: Noise originating from the A/C compressor, drive belt, or the A/C lines.
1 | Were you sent here from Symptoms or another diagnostic table? | Go to Step 2 | Go to Symptoms - HVAC Systems - Automatic
2 |

1. A/C system noises can be generally categorized into 3 areas:

• | Screeching, squealing, chirping noises

• | Moaning noises

• | Vibration/rattle noises

2. Start the engine.
3. Ensure that the A/C is ON.

Is a screeching, squealing noise heard when the A/C is engaged?

Go to Step 3

Go to Step 9

3 | With the engine OFF, inspect the drive belt for excessive wear. Refer to the appropriate procedure:

• | LINK

• | Drive Belt Falls Off and Excessive Wear Diagnosis

• | LINK

• | LINK

Is the drive belt excessively worn?

Go to Step 18

Go to Step 4

4 | Inspect the drive belt tension. Refer to the appropriate procedure:

• | LINK

• | Drive Belt Tensioner Diagnosis

• | LINK

• | LINK

• | LINK

Is the drive belt tension correct?

Go to Step 5

Go to Step 19

5 | Inspect the drive belt for excessive oil coverage. Is the drive belt covered with oil? | Go to Step 17 | Go to Step 6
6 |

1. Start the engine.
2. Ensure that the A/C is ON.
3. Inspect the compressor and the clutch.

Is the A/C compressor locked up?

Go to Step 24

Go to Step 7

7 | Is the A/C compressor clutch slipping? | Go to Step 23 | Go to Step 8
8 | Warning: Refer to Moving Parts and Hot Surfaces Warning in the Preface section. Using a stethoscope, listen to the A/C compressor for any abnormal noises. Is the compressor causing an abnormal noise? | Go to Step 15 | Go to Step 10
9 | Does a moaning noise exist when the A/C clutch is engaged? | Go to Step 10 | Go to Step 12
10 | Listen to the A/C compressor components and mounting for noise concerns using a stethoscope. Are any of these components loose, damaged, or excessively worn? | Go to Step 20 | Go to Step 11
11 |

1. Idle the engine.
2. Engage the A/C compressor clutch.
3. Using a stethoscope, move around the entire refrigerant plumbing system. Listening for any abnormal noises caused by a component of the A/C system touching another component.

Are any of the A/C components grounding out and causing a vibration noise?

Go to Step 22

Go to Step 13

12 | Does a vibration or rattle noise exist when the A/C clutch is engaged? | Go to Step 13 | Go to Step 14
13 | Does the noise stop when the A/C clutch is disengaged? | Go to Step 15 | Go to Step 25
14 |

1. Idle the engine in PARK with the A/C compressor clutch engaged.
2. Using a stethoscope, move around the entire A/C system testing for any abnormal noises caused by a component.

Do any of the A/C components cause an abnormal noise?

Go to Step 21

Go to Step 25

15 | Verify that the A/C system is properly charged. Refer to Refrigerant System Capacities Is the A/C system properly charged | Go to Step 26 | Go to Step 16
16 | Recharge the A/C system to specification. Refer to Refrigerant Recovery and Recharging Is the abnormal compressor noise still present? | Go to Step 24 | Go to Step 26
17 | Repair the oil leak. Refer to the appropriate procedure:

• | LINK engine

• | Oil Leak Diagnosis

• | LINK

• | LINK

• | LINK

Is the repair complete?

Go to Step 18

--

18 | Replace the drive belt. Refer to the appropriate procedure:

• | LINK

• | Drive Belt Replacement

• | LINK

• | LINK

Is the replacement complete?

Go to Step 26

--

19 | Replace the drive belt tensioner. Refer to the appropriate procedure:

• | LINK

• | Drive Belt Tensioner Replacement

• | LINK

• | LINK

Is the replacement complete?

Go to Step 26

--

20 | Repair or replace the A/C compressor mounting component. Is the repair complete? | Go to Step 26 | --
21 | Repair or replace the component which is causing the moaning concern as needed. Is the repair complete? | Go to Step 26 | --
22 | Correctly route or insulate the A/C component. Is the repair complete? | Go to Step 26 | --
23 | Replace the A/C compressor clutch. Refer to LINK. Is the repair complete | Go to Step 26 | --
24 | Replace the A/C compressor. Refer to Air Conditioning Compressor Replacement Is the repair complete? | Go to Step 26 | --
25 | The concern may be caused by an engine related component. Refer to Vibration Analysis - Engine Did you find and correct the condition? | Go to Step 26 | --
26 | Operate the system in order to verify the repair. Did you find and correct the condition? | System OK | Go to Step 2