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Noise Diagnosis - Air Conditioning (A/C) System

WARNING: This page is about a different car, the 2008 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.
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 .
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 .
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 A/C is ON.
  3. Inspect the compressor and the clutch.
Is the compressor locked up?		 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.
Do any of the A/C components cause an abnormal 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 to specification. 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.
Is the repair complete?		 Go to Step 25  -
18 Replace the drive belt. Refer to Air Conditioning Compressor and Power Steering Pump Belt Replacement .
Is the replacement complete?		 Go to Step 25  -
19 Replace the drive belt tensioner. Refer to Drive Belt Tensioner Removal - Right Side or Drive Belt Tensioner Removal - Left Side or Drive Belt Tensioner Installation - Left Side or Drive Belt Tensioner Installation - Right Side .
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 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 Falls Off and Excessive Wear Diagnosis
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 
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