A/C - Knocking Noise Heard at Idle With A/C ON
NUMBER: 24-007-05GROUP: Heating & A/C
DATE: April 2, 2005
THIS BULLETIN IS BEING PROVIDED IN ADVANCE. DO NOT ORDER PARTS OR PERFORM ANY ACTIONS RELATED TO THIS BULLETIN UNTIL MAY 2, 2005.
SUBJECT:
Knock Sound Heard At Idle With A/C On
OVERVIEW:
This bulletin involves installing a revised A/C compressor clutch hub and pulley.
MODELS:
2005-2006 (LX) 300/Charger/Magnum
NOTE:
This bulletin applies to vehicle equipped with a 3.5L Engine (Sales Code EGG) and built prior to July 1, 2005 (MDH 0701XX).
SYMPTOM/CONDITION:
Occasional or intermittent underhood knocking sound which occurs only with the A/C on and the engine at idle. The knocking sound is a light rapid knocking/tapping sound occurring at about 3 to 5 times per second.
DIAGNOSIS:
NOTE:
Due to the intermittent nature of this complaint, the following diagnosis must first be run to make sure the knocking noise is not related to another source.
1. Run the engine with A/C off for approximately 10 minutes or until engine has reached normal idle conditions (approximately 600 rpm).
2. While sitting in the passenger compartment, listen for evidence of the knocking noise with the A/C off. If no knocking noise is heard, perform the Repair Procedure.
3. If a knocking sound is heard, this bulletin does not apply and further diagnosis is required.
SPECIAL TOOLS/EQUIPMENT REQUIRED
PARTS REQUIRED
REPAIR PROCEDURE:
1. Disconnect and isolate the negative battery cable.
2. Remove the air cleaner assembly.
3. Remove the accessory drive belt.
4. Raise the vehicle on an appropriate hoist.
5. Remove the screws that secure the front belly pan to the underside of the vehicle. Remove the front belly pan from the underside of the vehicle.
6. Remove the bolt securing the clutch plate to the compressor shaft and discard the bolt. A band-type oil filter wrench or a strap wrench may be used to secure the clutch plate during bolt removal.
CAUTION:
Do not pry between the clutch plate and the pulley and bearing assembly to remove the clutch plate from the compressor shaft as this may damage the clutch plate.
7. Remove the clutch plate and shim(s) from the compressor. It may be necessary to tap the clutch plate lightly with a plastic mallet to release it from the splines on the compressor shaft.
8. Using 90° external snap ring pliers, remove the external snap ring that secures the pulley to the front A/C compressor, discard the snap ring, then slide the pulley off of the A/C compressor.
CAUTION:
When installing the pulley and bearing assembly, DO NOT mar the friction surfaces of the pulley or premature failure of the clutch will result.
9. Install the pulley and bearing assembly onto the A/C compressor.
CAUTION:
The snap ring must be fully and properly seated in the groove or it will vibrate out, resulting in a clutch failure and severe damage to the A/C compressor.
NOTE:
A new snap ring must be used to secure the pulley and bearing assembly to the A/C compressor. The bevel side of the snap ring must face outward.
10. Using 90° snap ring pliers, install the external snap ring that secures the pulley and bearing assembly to the A/C compressor. Be certain that the snap ring is fully and properly seated in the groove.
11. Install a trial stack of shims 4.1 mm (0.016 in.) thick in the clutch plate and over the attaching bolt.
12. Install the clutch plate and new bolt onto the compressor shaft.
13. Tighten the clutch plate retaining bolt to 19 Nm (168 in. lbs.).
NOTE:
The shims may compress after tightening the shaft bolt. Check the air gap in three or more places to verify the air gap is correct.
14. With the clutch plate assembled tight against the shim(s), measure the air gap between the clutch plate and the pulley faces with a 90° spark plug gap gauge, (Fig. 1). The air gap should be 0.35 - 0.60 mm (0.014 - 0.024 in.). If the proper air gap is not obtained, add or subtract shims as needed until the desired air gap is obtained.
15. Install the front belly pan.
16. Lower the vehicle.
17. Install the accessory drive belt. Reconnect the negative battery cable.
18. Install the air cleaner assembly.
19. Connect the negative battery cable.
20. Set the clock to the correct time.
POLICY:
Reimbursable within the provisions of the warranty.
TIME ALLOWANCE
FAILURE CODE
Disclaimer
This bulletin is supplied as technical information only and is not an authorization for repair.