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 HVAC Symptoms or another diagnostic table? | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

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

• | Screeching, squealing, or chirping noises

• | Moaning noises

• | Vibration/rattle noises

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

Do you hear a screeching, squealing noise when you engage the A/C?

Go to Step 3

Go to Step 9

3 | With the engine OFF, inspect the drive belt for excessive wear. Refer to Drive Belt Falls Off and Excessive Wear Diagnosis for the 3.6L engine or Drive Belt Falls Off and Excessive Wear Diagnosis for the 4.6L engine. Is the drive belt excessively worn? | Go to Step 18 | Go to Step 4
4 | Inspect the drive belt tension. Refer to Drive Belt Rumbling and Vibration Diagnosis for the 3.6L engine or Drive Belt Rumbling and Vibration Diagnosis for the 4.6L engine. 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 front and rear A/C is ON.
3. Inspect the compressor and the clutch.

Is the compressor clutch locked?

Go to Step 23

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. Start 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 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 listening for any abnormal noises caused by a component.

Are any of the A/C components causing a noise?

Go to Step 21

Go to Step 24

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 24 | Go to Step 16
16 | Recharge the A/C system. Refer to Refrigerant Recovery and Recharging . Is the abnormal compressor noise still present? | Go to Step 24 | Go to Step 25
17 | Repair the oil leak. Refer to the appropriate repair procedure in Engine Mechanical. Is the repair complete? | Go to Step 25 | --
18 | Replace the drive belt. Refer to Air Conditioning Compressor and Power Steering Pump Belt Replacement for the 3.6L engine or Water Pump and Air Conditioning Compressor and Power Steering Pump Belt Replacement for the 4.6L engine. Is the replacement complete? | Go to Step 25 | --
19 | Replace the drive belt tensioner. Refer to Air Conditioning Compressor and Power Steering Pump Belt Tensioner Replacement or Drive Belt Tensioner Replacement - Air Conditioning, Power Steering, and Water Pump . Is the replacement complete? | Go to Step 25 | --
20 | Repair or replace the A/C compressor mounting component. Is the repair complete? | Go to Step 25 | --
21 | Repair or replace the component which is causing the moaning concern as needed. Is the repair complete? | Go to Step 25 | --
22 | Correctly route or insulate the A/C component. Is the repair complete? | Go to Step 25 | --
23 | Replace the A/C compressor. Refer to Air Conditioning Compressor Replacement . Is the replacement complete? | Go to Step 25 | --
24 | The concern may be caused by an engine related component. Refer to Drive Belt Rumbling and Vibration Diagnosis for the 3.6L engine or Drive Belt Rumbling and Vibration Diagnosis for the 4.6L engine. Did you find and correct the condition? | Go to Step 25 | --
25 | Operate the system in order to verify the repair. Did you find and correct the condition? | System OK | Go to Step 2