A/C - ACC Production Change

91mercedes04

REF.NO. 83/75


TO: OUR MERCEDES-BENZ PASSENGER CAR DEALERS

DATE: June 1991


SUBJECT: MODELS 124 AND 126 MODIFICATIONS OF THE AUTOMATIC CLIMATE CONTROL
A. MODIFIED WATER FLOW CIRCUIT IN THE HEATER CORE ON MODEL 124
B. MODIFICATION OF THE COMPRESSOR SHUTOFF ON AUTOMATIC CLIMATE CONTROL, MODELS 124 AND 126

Figure 1:

Figure 2:

A. Modified Water Flow Circuit in the Heater Core on Model 124

Since May 1990, a heater core with modified water flow circuit and a new version monovalve (Figure 2) are installed. They guarantee improved removal of air trapped in the heater core (Figure 1 ).


Effective Serial Number

Model As of Chassis End Number

124 (except for station wagon) B249 838

station wagon F146 108


Parts Information

Qty. Part Name

1 Heat exchanger (heater core)

Figure 3:

Note: The modified heater core cannot be installed in the previous version heater case.

Additionally, if the new version heater core must be exchanged, the entire heater/air conditioning case must be removed.

Figure 4:

To remove the heater core with the pipes, the support for the vacuum components (8, Figure 4) must be unbolted (3 bolts, arrow) and the linkage rod for the main air flap (arrow, Figure 5) must be unclipped.


Note: Do not install Anti-Gurgle Kit(s) (MBNA 83/33a of 5/1/91) in vehicles with the modified heater core.


B. Modification of the Compressor Shutoff on Automatic Climate Control Models 124 and 126

The compressor shoutoff for gasoline-powered vehicles is modified as follows:

The compressor cycles (20 seconds on, 20 seconds off) if the coolant temperature measured at sensor B10/8 is abovev 122~ C (previously 117~ C). Compressor emergency shutoff occurs at coolant temperatures above 128~ C (previously 122~ C).

After this modification, the pushbutton control unit (N22) is the same for gasoline and diesel powered vehicles. This version can be installed in earlier production vehicles (as of September 1987).

Parts Information

Qty. Part Name Part Number

1 Monovalve 001 830 20 84


In Case of Warranty

Operation: Heater core, air in system (water noise)

Damage Code Operation Number Time Model(s)

83201 86