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Questions and Answers

Mercedes E320 Climate Control

Q. I have a 1995 Mercedes E320 wagon with A/C problems. I read your explanation of the 300D Automatic Climate Control (ACC) and believe mine would be similar in the way it works. My systems compressor runs fine as it cycles with the temperature wheel. Air deflects to proper places when heating and vent. What it does is when A/C is needed it will only blow out cooled air through the center vents.

Mercedes E320 Climate Control

Outer vents seem to blow outdoor air. To further confuse me the system only blows the cooled air out the center vents when it is on low fan. If you set it on ACC (Climate Control) or on high fan it blows outdoor air through all vents. I would appreciate any input you might give me.


The door vacuum motors are controlled by the Switchover Valve Unit (Y7). The switchover valves, which are located beneath the dash panel on the heater box, connect the vacuum source to the various vacuum elements.

The switchover valve unit consists of a plastic vacuum manifold, which is fitted with electrically operated solenoid valves.

While the engine is running, vacuum is supplied to the switchover valve manifold. A vacuum reservoir supplements the system during periods of low engine vacuum and a check valve prevents system bleed off. When the operator selects a climate control function the push-button control unit energizes the appropriate electric solenoid of the switchover valve unit. Vacuum from the engine and or the vacuum reservoir is connected via the switchover valves to the corresponding vacuum element(s) opening or closing the flaps.

You can check the door operation by unplugging a vacuum line, one at a time, and applying vacuum to check each door vacuum motor for proper operation. If all the door vacuum motors are working, then the problem is probably in the ACC unit itself.

Mercedes E320 Climate Control

Additional Information provided courtesy of ALLDATA

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