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For 1990-2009 cars only

Noise Diagnosis - Air Conditioning (A/C) System with HP5

Step

Action

Yes

No

DEFINITION: Noise originating from the A/C compressor, 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 - Manual or Symptoms - HVAC Systems - Automatic.

2

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

    • Screeching, squealing, chirping noises
    • Moaning noises
    • Vibration/rattle noises
  1. Start the engine.
  2. 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

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

Is the A/C compressor locked up?

Go to Step 16

Go to Step 4

4

Caution: 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 11

Go to Step 6

5

Does a moaning noise exist when the A/C compressor is turned on?

Go to Step 6

Go to Step 8

6

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 13

Go to Step 7

7

  1. Idle the engine.
  2. Turn on the A/C compressor.
  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 15

Go to Step 9

8

Does a vibration or rattle noise exist when the A/C compressor is turned on?

Go to Step 9

Go to Step 10

9

Does the noise stop when the A/C compressor is turned off?

Go to Step 11

Go to Step 17

10

  1. Idle the engine in PARK with the A/C compressor turned on.
  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 14

Go to Step 17

11

Verify that the A/C system is properly charged. Refer to Refrigerant System Capacities.

Is the A/C system properly charged?

Go to Step 18

Go to Step 12

12

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

Is the abnormal compressor noise still present?

Go to Step 16

Go to Step 18

13

Repair or replace the A/C compressor mounting component.

Is the repair complete?

Go to Step 18

--

14

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

Is the repair complete?

Go to Step 18

--

15

Correctly route or insulate the A/C component.

Is the repair complete?

Go to Step 18

--

16

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

Is the repair complete?

Go to Step 18

--

17

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 18

--

18

Operate the system in order to verify the repair.

Did you find and correct the condition?

System OK

Go to Step 2

Noise Diagnosis - Air Conditioning (A/C) System without HP5

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 - Manual or Symptoms - HVAC Systems - Automatic.

2

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

    • Screeching, squealing, chirping noises
    • Moaning noises
    • Vibration/rattle noises
  1. Start the engine.
  2. 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:

    •  Drive Belt Falls Off and Excessive Wear Diagnosis for the 2.4L (LE5) engine
    •  Drive Belt Falls Off and Excessive Wear Diagnosis for the 3.5L (LZ4)engine
    •  Drive Belt Falls Off and Excessive Wear Diagnosis for the 3.6L (LY7) engine

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:

    •  Drive Belt Tensioner Diagnosis for the 2.4L (LE5) engine
    •  Drive Belt Tensioner Diagnosis for the 3.5L (LZ4)engine
    •  Drive Belt Tensioner Diagnosis for the 3.6L (LY7) engine

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?

For LE5/LZ4/LY7 Go to Step 23

or

For LAT Go to Step 24

Go to Step 8

8

Caution: 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:

    •  Oil Leak Diagnosis for the 2.4L (LE5) engine
    •  Oil Leak Diagnosis for the 3.5L (LZ4)engine
    •  Drive Belt Replacement for the 3.6L (LY7) engine

Is the repair complete?

Go to Step 26

--

18

Replace the drive belt. Refer to the appropriate procedure:

    •  Drive Belt Replacement for the 2.4L (LE5) engine
    •  Drive Belt Replacement for the 3.5L (LZ4)engine
    •  Drive Belt Replacement for the 3.6L (LY7) engine

Is the repair complete?

Go to Step 26

--

19

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

    •  Drive Belt Tensioner Replacement for the 2.4L (LE5) engine
    •  Drive Belt Tensioner Replacement for the 3.5L (LZ4)engine
    •  Drive Belt Tensioner Replacement for the 3.6L (LY7) engine

Is the repair 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 Compressor Clutch Assembly Replacement.

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