A/C - Rising/Receding/Tapping Noise/DTC' Set
87 06 05Nov. 2, 2006
2012983/1
Rising and receding or tapping noise from AC; DTC 00716, 00735 or 01087 may be stored
Vehicle Information
Condition
Customer may complain of rising and receding noise coming from the blower motor. The customer often also complains about a tapping noise from the air conditioning's regulator motors.
The air conditioning's fault memory may log the following DTCs: 00716 regulator motor for circulation air flap mechanical fault or 00735-010 potentiometer in the regulator motor for circulation air flap -G143 disruption/short circuit to positive or 01087 basic settings of the air conditioning not performed, saved.
Technical Background
Water enters the regulator motor housing for circulation air flap V113 in the plenum chamber. Then the regulator motor cannot reach its end positions, and the basic setting process of the air conditioning is stopped. When driving, the customer constantly hears the activation of the air recirculation motor. The contact points between the regulator motor and wiring loom are severely corroded. See illustration.
On vehicles with a solar roof, this can also cause an increased closed-circuit current.
Production Solution
Changed process for sealing the air circulation regulator motor.
Service
Perform the guided fault finding.
If DTC 00716, 01087 or 00735 are logged in the fault memory of the air conditioning, the housing of the regulator motor for the circulation air flap must be sealed off and the regulator motor and its pins must be replaced. You need the repair kit 4E0 898 998 (regulator motor with the necessary pins), and the silicon sealer D176 001 A3.
Remove the regulator motor for circulation air flap V 113 according to the repair manual. This regulator motor is the back one of the two visible regulator motors on the air conditioning unit in the plenum chamber, therefore the windshield wipers must also be completely removed. The ignition must not be switched on.
The holder of the coolant reservoir (see illustration, point 1) is fitted in the plenum chamber, at point 4 in the illustration below. The windshield wiper motor is on point 5. The windshield wiper motor is only accessible if the holder of the coolant reservoir (point 1) is unscrewed on point 4.
Remove the left wheel, loosen the left rear wheel arch liner (point 3), and take off the coolant reservoir plug (point 2). Loosen a clamping bolt and remove the coolant reservoir (point 1) from its holder. Push the coolant reservoir upward by hand from the wheel arch side. (See the red arrow in the illustration below.) Loosen the size 10 nut on point 4 that secures the holder. Finally, loosen the windshield wiper motor on point 5 in the plenum chamber.
The blue plug of the regulator motor must have the damage shown on the illustration above. The carrier plate, labeled point 1 in the illustration, must be reused. It is not included in repair kit 4E0 898 998.
Replace all pins in the blue plug, and use a new plug housing from the repair kit.
Remove the plug of regulator motor and dismantle it. Loosen the catch on the housing as shown in the illustration, and push on the plug housing.
Press in the locking mechanism of the pins with a screwdriver and pull out the individual pins.
Push out, replace, refit and push in every pin individually. This prevents the cables from being mixed up when pushed into the new plug housing. Disconnect the pin on the point labeled 3 in the illustration below, and remove the cable insulation to ensure a sufficient cable length.
On all affected vehicles, continuously pour the silicon D 176 001 A3 into the plug seal on the wiring loom as shown in the illustration.
On all affected vehicles, continuously pour the silicon D 176 001 A3 into the plug seal on the wiring loom as shown in the illustration below.
On vehicles up to chassis number 4E_4N015369, place a 3 mm wide butyl cord in the groove of the housing, as shown in the illustration. Cut through the center of butyl cord AKL 450 005 05 with a pair of scissors to split its diameter in half.
On vehicles with chassis number from 4E_4N015369, apply a 3mm wide bead with silicon D 176 001 A3 on the cover of the regulator motor, as shown in point 1 of the illustration.
Fit the regulator motor and make sure that the cables are not too tight. Refit the carrier plate and tighten the regulator motor.
Fit the cover of the regulator motor. On vehicles with chassis number from 4E_4N015369, the silicon on the point in red in the illustration must escape and seal off the cover.The illustration shows the correct sealing with the butyl cord on a vehicle with chassis number before 4E_4N015369.
It is only necessary on vehicles up to chassis number 4E_4N015369 to generously seal off the rubber grommet with the silicon paste D 176 001 A3, as shown in the illustration. Before applying the sealer, thoroughly clean the housing. Make sure that the lower grommet area is tight.
Vehicles with chassis numbers from 4E 4N 015369 have a cover similar to the one labeled point 4 in the illustration. In these vehicles, the rubber grommet does not have to be sealed off with the silicon paste.
Perform the basic settings on the AC control panel, address code 08. Delete the logged faults. Refit all removed parts.
Warranty
Required Parts and Tools
All part and service references provided in this TSB are subject to change and/or removal. Always check with your Parts Dept. and service manuals for the latest information.