Acc Pushbutton Control Unit Inspection/Replacement (83/39)

ACC PUSHBUTTON CONTROL UNIT INSPECTION/REPLACEMENT

TECHNICAL SERVICE BULLETIN

MODEL 124 - AUTOMATIC CLIMATE CONTROL PUSHBUTTON CONTROL UNIT INSPECTION/REPLACEMENT

Model(s): Mercedes-Benz 300 D, 300 E, 300 CE, 300 TE, 300 E 4MATIC, 300 TE 4MATIC Group: 83 - Climate Control System, Automatic/Tempmatic A/C

Bulletin No.: MBNA 83/39

Date: November 1991

SERVICE INFORMATION

In vehicles within the Effective Serial Number Range below. 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.

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 USA Version (°F)	Part Number 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