Its the Aux.Fan relay I believe. Its in the relay box under the fuses which are under the hood. Its a blue relay, which when searched for by mercedes is superceded by the green relay which is also used as a fuel pump relay in the trunck. This is what I was told over the phone. The blue relay under the hood keeps blowing its fuse, and the fuse is a blue 15A fuse also. Has anyone else had similar probs? Thanks guys.