[Don's ML]

I Bought a 2006 ML 350 in early summer and have had good luck with the vehicle. It has been a hot summer and the AC cooled just fine in the hot weather. I have always noticed a whine noise from the AC compressor that sounded almost like a bad alternator. The noise goes away when you turn the Auto air system off. checking under the hood I could not find any strange noise from anything until I switched on the AC. THe noise is more of a low growl at idle, that gets louder with engine speed and turns into a whine noise. Now that it is cooler and the fan speed is slower the noise is getting on my nerves. Like I said it is cooling fine just alot of noise. Has anyone had this noise and if so what did you do for it. A compressor from Mercedes is about $1,000.00 from the parts dept. A new Denso OE compressor is about half the price from NAPA. They look the same. Mercedes also offers a reman unit, but I don't know the price yet. I would not worry about this with winter getting close, but I am afraid that it may lock up and cause me to loose the belt if I just let it go.

 

[mbtech22]

Should the compressor lock up, there is a break-away system designed into the front of the a/c pulley which will allow the belt to continue to freewheel. This only works if the compressor itself locks, and not the bearing inside the pulley. As for your noise, I would recommend checking the refridgerant charge and adding a little extra oil during recharge. If the noise is still present, go with the reman MB compressor. Don't forget, you will have to replace the drier, seals, and refridgerant so factor that into the cost as well. If the compressor does sieze, you will also have to flush the system of any contamination from the bad compressor.