Campaign - ACC Pushbutton Control Unit
91mercedes03
REF. NO.: MBNA 83/39
TO: OUR MERCEDES-BENZ PASSENGER CAR DEALERS
DATE: November 1991
SUBJECT: MODEL 124 AUTOMATIC CLIMATE CONTROL PUSHBUTTON CONTROL UNIT INSPECTION/REPLACEMENT
In vehicles within the Effective Serial Number Range, the pushbutton control unit for the automatic climate control (ACC) must be checked prior to any other repair in cases of climate control complaints, or during the vehicle's next scheduled maintenance or repair. If a customer's vehicle within the Effective Serial Number Range has just recently been serviced i.e. the vehicle is not scheduled for another service in the near future, we suggest that you contact the customer to schedule an appointment to have the pushbutton control unit checked.
Pushbutton control units manufactured by Bosch, part no. 124 830 33 85 (Canada version [~C], part no. 124 830 24 85), are incorrectly soldered causing the unit to fail. Thus, the automatic climate control will only operate in the heating and defrosting mode.
The affected pushbutton control units are marked with one of the following production codes:
163, 164, 165, 166.
Control units with these production codes must be replaced as they will ultimately fail to function properly.
Bosch pushbutton control units as of production code 167 are correctly manufactured.
Pushbutton control units manufactured by Kammerer. part no. 124 830 31 85 (Canada version [~C], part no. 124 830 22 85), are correctly soldered, i.e. they do not have this problem.
Effective Serial Number Range
Model From Chassis End Number To Chassis End Number
124 1B 501718 1B 574453
124 1F 180488 1F 191943
Determine whether or not the automatic climate control (ACC) pushbutton control unit must be replaced by inspecting which version is installed.
Procedure
1. Remove center dashboard wooden panel by removing the two screws at the lower edge just above the radio.
2. Inspect whether the pushbutton control unit is manufactured by Kammerer. Kammerer units are identified by the letters "MK" enclosed in a box on face of the unit. If a Kammerer unit is installed, replacement is not necessary. The wooden panel may be reinstalled.
3. If control unit is not marked on face of unit, then the unit installed is manufactured by Bosch.
4. Remove (Bosch) automatic climate control (ACC) pushbutton control unit (see SMS, Repair Instructions, Automatic Climate Control, Model 124, Job No. 635).
5. Inspect production code information on back or side (frame) of control unit.
6. Replace (Bosch) control unit if production code is 163, 164, 165, or 166. Do not replace control unit if production code is below or above this range.
7. Reinstall control unit and wooden panel.
Parts Information
Part Name Manufacturer Part Number Part Number
USA Version (~F) Canada Version (~C)
ACC pushbutton control unit Bosch 124 830 33 85 124 830 24 85
ACC pushbutton control unit Kammerer 124 830 31 85 124 830 22 85
Existing stock supplies of Bosch ACC pushbutton control units affected by this Service Information are to be returned to your facing PDC for credit.
In Case of Warranty
Operation: 02-1050 Inspect ACC pushbutton control unit manufacturer
(This operation no. applies to vehicles with Kammerer units)
02-1058 Inspect ACC pushbutton control unit production code
(This operation no. applies to vehicles with Bosch units)
02-1059 Inspect and replace ACC pushbutton control unit
(Bosch units only)
Only one operation no. can be applied.
Damage Code Operation Number Time Model(s)
83 940 42 02-1050 0.1 hrs. 25/82/83/85/86/88
83 940 42 02-1058 0.2 hrs. 25/82/83/85/86/88
83 940 42 02-1059 0.3 hrs. 25/82/83/85/86/88
Return of ACC Pushbutton Control Units Removed from Vehicles Affected by this Campaign
Control units should be returned to MBNA WARRANTY INSPECTION, 1 Glenview Road, Montvale, NJ
07645.