Hello!
I hear a hissing sound from behind the dashboard. It gets stronger, then quiets down, sometimes stops, and then starts all over again. It doesn't matter whether the air conditioner is on or off, the hissing noise is still there. The air conditioning refrigerant has been topped up, but the hissing noise is still there. If I turn off the internal air circulation, the noise stops immediately. Very annoying. Where should I look for the problem? Should I try to replace the internal fan?
W211 E220 CDI 2008 sedan
I hear a hissing sound from behind the dashboard. It gets stronger, then quiets down, sometimes stops, and then starts all over again. It doesn't matter whether the air conditioner is on or off, the hissing noise is still there. The air conditioning refrigerant has been topped up, but the hissing noise is still there. If I turn off the internal air circulation, the noise stops immediately. Very annoying. Where should I look for the problem? Should I try to replace the internal fan?
W211 E220 CDI 2008 sedan
BlackML550
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May 17, 2026
- Join DateJun 2014
- LocationMelbourne, Australia
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- Vehicle(s) I drive2010 ML550 VIN WDC1641722A564750, 2010 B180
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Does the noise change with vehicle speed? Check your cabin fliters as well to make sure they're seated properly.
