Of course, right after my 3/36 warranty expired, I started having this awful sound when the blower fan is directing air to the defroster or floor vents. It sounds like a broken piece of plastic is being thrown around in the system. I can sometimes turn the fan to the highest speed and it will somehow get this "thing" to settle down into a place where it doesn't get flung around. But eventually, it keeps coming back. Interesting thing is that, when the air is just on the upper vents (not defrost), it doesn't do it.

Has anyone else experienced this? It's driving me insane, so I'll definitely get it fixed next time I take it in. I'm just wondering if I have an expensive repair coming, or if this might be something relatively simple.

Thanks in advance for any advice you might have!

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<b>2005 Liberty CRD Limited</b>
Atlantic Blue, Navigation, Sirius,
Park Distance Control,
Parrot Bluetooth system;
Custom heated, leather seats (black on the side bolsters, Atlantic Blue center);
Skid plate package, Michelin Cross-Terrains
<b>2007 Mercedes ML320 CDI (twin-turbo V6 diesel)
2008 Mercedes C350 Sport

Judging by the FSM there is a door that controls air to the defroster and floor (at least its part of the whole system). Something probably fell in one of your defroster vents and its just light enough to rattle around when the blower motor is on. I had this happen with a receipt once in another vehicle and it whistled when I would turn the fan above the lowest setting. It would probably take a tech a couple of hours to find the source of the noise and fix it (which will probably just entail removing whatever is rattling around, but could be something that came loose or broke off inside the housing. In which case they will want to replace it. Could cost a couple hundred bucks (mostly for the tech's time). The just a guess on my part though.

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'06 Stone White, CRD Limited
CRD Frankenlift II, Rock Lizard Rear Bumper, Mann Provent, GDE FT-ECO Tune, "Euro Torque Converter, Transgo 545RFE-H2 Shift Kit, 245/75 MT/R's on Moabs, Full Mopar Skids, Front Tow Hooks, CAT 2 Fuel filter and bleeder valve mod, Fumoto valve, Wahlbro Lift Pump, Custom 2 1/2" Exhaust