A/C - Compressor Noise/Poor A/C Performance
Date: March 17, 2009Order No.: P-B-83.55/119a
Supersedes: P-B-83.55/119 dated August 18, 2008
Group: 83
Revision History
Revision Date Purpose
a 3/17/09 Section I Revised / Note Added in Section II - No Cooling (Warranty Procedure)
- 8/18/08 Initial issue
SUBJECT:
All Model 203.040/740, Equipped with M271 Engine
Replacement of Refrigerant Compressor Belt Pulley Due to Noise Complaints or No Cooling
If you receive customer reports in the above model vehicles of noises at the refrigerant compressor, the cause could be a malfunctioning belt pulley or belt pulley bearing. The pulley and pulley bearing can be diagnosed and replaced with the compressor still installed in the vehicle by following the procedures below.
There may be no cooling due to the torque limiter in the drive hub of the pulley being sheared and the compressor not turning. Follow instructions for no cooling starting with "Section II - No Cooling".
Section I - Noise Complaint
1. Test for alternator freewheel movement
1.1 If the alternator freewheel is NOT seized, continue with step 2.
1.2 If the alternator freewheel is seized, replace the alternator freewheel.
1.3 Check if the shaft for refrigerant compressor can be turned: Dismantle belt pulley for refrigerant compressor as per WIS document AR83.55-P-7685. Carefully turn the compressor shaft, after dismantling the belt pulley, using a suitable socket.
^ If the shaft can be turned: Fit new belt pulley since the defective alternator freewheel damaged the limiter of the compressor pulley. Refer to WIS document AR83.33-P-7685
^ If the shaft cannot be turned: Replace complete refrigerant compressor.
2. Noise diagnosis:
Note:
If there is also a cooling performance complaint, the noise could be caused by low refrigerant level: Perform a Refrigerant Circuit Test as per SDS and follow instructions for corrective actions.
3. Locate the noise by duplicating the conditions under which the complaint occurred.
4. Before the belt pulley on the refrigerant compressor is replaced, verify that the following components in the belt drive are not the source of the noise and repair as required.
^ Alternator, Power steering pump, water pump
Note:
Only for noise that is audible for both activated and deactivated air conditioning, continue with step 7.
If this condition does not occur:
5. Check fill level of refrigerant for noise with activated air conditioning.
6. Check the belt drive for noise with deactivated air conditioning.
7. It is not possible to install a shorter belt to bypass the AC compressor due to belt routing.
8. Follow AC compressor pulley replacement instructions from step 6 to 19.
9. Refer to Figure 2 for component number references. Remove the belt pulley circlip (Figure 2, Part 6). With plastic belt pulleys, it is possible to insert a screwdriver under the circlip (Figure 2, Part 6) and pry it out of the groove.
10. Remove hub (Figure 2, Part 1) using a socket and counter hold tool W112 589 07 04 00. Use a small magnet to remove flat washer from shaft.
Note:
There are two versions of the compressor shaft, a 7mm hex and one with two flats. The shaft with two flats requires the use of socket W112 589 02 09 00. To loosen 7mm hex head, ensure that proper METRIC tool is utilized. To loosen the pulley:
Warning!
It is not a left hand thread!
Method A (Preferred and shown in picture below): Hold the compressor shaft stationary and turn the drive hub counter clockwise to loosen (Figure 3a and 3b). Turn the hub clockwise to tighten.
Method B: Hold the drive hub stationary and turn the compressor shaft clockwise to loosen. Turn counter clockwise to tighten.
11. Remove snap ring (Figure 2, Part 4) for pulley bearing.
12. Remove belt pulley (Figure 2, Part 2) from the end of compressor housing.
Note:
Do not apply a pulling force in an axial direction to the refrigerant compressor shaft. Components damaged due to improper repair procedures may
be subject to debit.
13. Assemble the rubber dampers (Figure 2, Part 5) into new pulley the as shown in example A in Figure 4 and Figure 5. Make note of the direction of the curvature of the rubber dampers and install them over the reinforcing webs in the pulley, not in the spaces between the webs.
14. Remove snap ring (Figure 2, Part 4) for pulley bearing.
15. Install the snap ring (Figure 2, 4) for pulley bearing with its flat side facing the refrigerant compressor. Make sure the snap ring is seated correctly in the groove.
Note:
Use snap ring pliers with 90° tips that have a minimum reach of 19 mm (0.75").
16. Install washer (Figure 2, 3). Make sure it is flat against the shoulder of the shaft.
17. Install hub (Figure 2, 1) so the drive fingers are inserted into the gaps between the ends of the rubber dampers. Screw the hub onto the compressor shaft clockwise and torque to 35 Nm. The hub continues to tighten when in the compressor is in operation.
18. Install circlip (Figure 2, 6) into the belt pulley. Make sure it is seated in the groove of the pulley.
19. Install a new standard length poly-V-belt. Start engine and verify correct belt operation.
20. Install lower engine paneling.
Section II - No Cooling
1. Remove induction silencer as per WIS document AR09.41-P-6825T.
2. Remove the poly-V-belt.
3. Inspect the AC compressor to see if the shaft is not turning due to a sheared torque limiter in the drive hub. If the hub has sheared follow replacement instructions from step 6 to 19 of section I.
4. The cause of the hub shearing could be a seized alternator pulley freewheel. The alternator pulley needs to be inspected as follows. Pry the plastic cover off the end of the alternator pulley. Insert socket wrench tool W602 589 00 10 00 to hold the shaft from turning. Turn the pulley clockwise and it should lock. Turn the pulley counterclockwise, it should freewheel.
5. If the pulley did not freewheel it needs to be replaced. Use a 17mm wrench on the end of the socket wrench tool and hold it stationary (allow it to contact the frame/sub frame). Insert M10 socket W601 589 00 10 00 through the center of the socket wrench tool and into the end of the alternator shaft and turn the M10 socket clockwise to remove the pulley (Figure 3b).
6. Install new pulley and tighten with the M10 socket counterclockwise to 80 Nm. Use a torque wrench that functions in both directions. Install new plastic cover on end of pulley. It is important to follow loosening and tightening instructions as described.
Note:
A seized alternator pulley freewheel will cause the belt tensioner to oscillate back and forth when the engine is running.
Note:
Important concerning warranty procedure:
Before replacing parts, make absolutely certain that the belt pulley and not the entire refrigerant compressor is causing the noise problem. Compressors returned for warranty inspection that proves to have damage to the pulley will be re-debited and only the costs for replacement of the pulley replacement will be reimbursed.
When components of the AC system are replaced and then returned for warranty inspection, a control unit log must be included with the component from now on. SDS versions 09/2006 and higher include the menu item "Control unit log" to facilitate printing. This menu item automatically complies the following data which can then be printed:
^ Control units
^ Vehicle data
^ Customer complaint
^ Fault memory
^ Freeze frame data
^ Quick test
Note:
To ensure correct inspection of the component, it is important to complete the field "Customer complaint (remarks on damage)". This must include a meaningful fitter's findings report and any other information available. If the refrigerant compressor was replaced, it is absolutely essential to state the quantity of refrigerant extracted.
Special Tools
Parts Information
In Case of Warranty, use the table.