Hello,

New forum member, first time poster.

My 2011 E350 has suddenly started making a growling noise at about 53,000 miles. Noise seems to be on a 30-second cycle, about 9 seconds on and 21 seconds off. Noise most noticeable while stopped and idling, but I'm sure it's only being masked by road and engine noise when moving. I looked under the hood, noise is harder to hear with hood open, but seems to be emanating from underneath fan shroud, and I could feel a vibration in conjunction with the noise. Fan itself looked to spinning fine, and not cycling on and off with the noise.

Any idea what this could be? Thanks for the help!

 

The a/c compressor cycles, does it do it when a/c or defroster are off? Could be bad compressor or compressor clutch.