Technical Service Bulletins

Mercedes-Benz A/C Issues

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Mercedes-Benz A/C Issues

If the owner of a 2006 Mercedes Benz E350 Wagon complains about poor air conditioning operation and replacing the A/C control module does not repair the problem, erasing memory and performing a reset via circuit 30 may resolve the issue.

The sensors or actuator of the climate control system that are networked to the A/C bus can completely disable the A/C bus if they are not operating. Check the sensors, actuator motors and SDS for fault codes. If communication faults are stored, then the operating unit is not the cause.

The multi-zone sun sensors have a significant influence on the temperature control. The sun shining at a specific angle can result in different outlet air temperatures and blower output on different sides of the interior. This effect is also possible on a cloudy day because of UV radiation. Adjustment of the interior temperature is also heavily influenced by environmental conditions (heat from the transmission tunnel, heat from the radio, etc.). Replacing the operating unit will not change the control response.

At very high speeds, the refrigerant compressor output is lowered to provide the engine with extra power. This can cause the report of “blower output too warm.” Since this is a normal function, replacing the A/C control module is not a solution.

Check all steps in the diagnosis tree found on Star TeklInfo EDAC Non EDAC Guides Vehicle Heating, Ventilation and Air Conditioning.

Erase all memory

Perform system reset via circuit 30.

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