DEFINITION: Noise originating from the A/C compressor, drive belt or the A/C lines.

Were you sent here from Symptoms or another diagnostic table?

Go to Step 2

Go to Symptoms - HVAC Systems - Automatic

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

•	Screeching, Squealing, Chirping noises

•	Moaning noises

•	Vibration/Rattle noises

2. Engage the Park brake.
3. Start the engine.
4. Ensure that the 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

With the engine OFF, inspect the A/C drive belt for excessive wear. Refer to Drive Belt Falls Off and Excessive Wear Diagnosis.

Is the drive belt excessively worn?

Go to Step 18

Go to Step 4

Inspect the A/C drive belt tensioner. Refer to Drive Belt Tensioner Diagnosis.

Is the drive belt tension correct?

Go to Step 5

Go to Step 19

Inspect the drive belt for excessive oil coverage.

Is the drive belt covered with oil?

Go to Step 17

Go to Step 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 23

Go to Step 7

Is the A/C compressor clutch slipping?

Go to Step 23

Go to Step 8

Caution: Avoid contact with moving parts and hot surfaces while working around a running engine in order to prevent physical injury.

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

Does a moaning noise exist when the A/C clutch is engaged?

Go to Step 10

Go to Step 12

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

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 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

Does a vibration or rattle noise exist when the A/C clutch is engaged?

Go to Step 13

Go to Step 14

Does the noise stop when the A/C clutch is disengaged?

Go to Step 15

Go to Step 24

1. Idle the engine 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.

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

Go to Step 21

Go to Step 24

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

Recharge the A/C system to specification. Refer to Refrigerant Recovery and Recharging .

Is the abnormal compressor noise still present?

Go to Step 23

Go to Step 25

Repair the oil leak. Refer to Oil Leak Diagnosis.

Is the repair complete?

Go to Step 25

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Replace the A/C drive belt. Refer to Air Conditioning Compressor Belt Replacement.

Is the replacement complete?

Go to Step 25

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Replace the A/C drive belt tensioner. Refer to Drive Belt Tensioner Replacement - Air Conditioning.

Is the replacement complete?

Go to Step 25

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Repair or replace the A/C compressor mounting component.

Is the repair complete?

Go to Step 25

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Repair or replace the component which is causing the moaning concern as needed.

Is the repair complete?

Go to Step 25

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Correctly route or insulate the A/C component.

Is the repair complete?

Go to Step 25

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Replace the A/C compressor. Refer to Air Conditioning Compressor Replacement .

Is the replacement complete?

Go to Step 25

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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 25

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Operate the system in order to verify the repair.

Did you find and correct the condition?

System OK

Go to Step 2