For 1990-2009 cars

Step | Action | Yes | No
--- | --- | --- | ---
1 | Were you sent here from HVAC Symptoms? | Go to Step 2 | Go to Symptoms - HVAC Systems - Manual
2 |

1. A/C system noises can be generally categorized into three 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 Drive Belt Excessive Wear Diagnosis in Engine Mechanical - 3.4L or Drive Belt Excessive Wear Diagnosis in Engine Mechanical - 2.2L. Is the drive belt excessively worn? | Go to Step 18 | Go to Step 4
4 | Inspect the drive belt tension. Refer to Drive Belt Tensioner Diagnosis in Engine Mechanical - 3.4L or Drive Belt Tensioner Diagnosis in Engine Mechanical - 2.2L. Is the drive belt tension correct? | Go to Step 19 | Go to Step 5
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 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 | 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, inspecting for any abnormal noises caused by component ground-out.

Are any of the A/C components grounding out and causing a 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 14
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 25 | Go to Step 26
17 | Repair the oil leak. Refer to the appropriate repair procedure in Engine Mechanical. Is the repair complete? | Go to Step 26 | --
18 | Replace the drive belt. Refer to Drive Belt Replacement in Engine Mechanical - 3.4L or Drive Belt Replacement in Engine Mechanical - 2.2L. Is the replacement complete? | Go to Step 26 | --
19 | Replace the drive belt tensioner. Refer to Drive Belt Tensioner Replacement in Engine Mechanical - 3.4L or Drive Belt Tensioner Replacement in Engine Mechanical 2.2L. 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 Clutch Rotor and/or Bearing Replacement . Is the replacement complete? | Go to Step 26 | --
24 | Replace the A/C compressor. Refer to Air Conditioning Compressor Replacement . Is the replacement complete? | Go to Step 26 | --
25 | The concern may be caused by an engine related component. Refer to Vibration Analysis - Engine in Vibration Diagnosis and Correction. Did you find and correct the condition? | Go to Step 26 | --
26 | Operate the system in order to verify the repair. Is the system OK? | System OK | Go to Step 2