Need a little help

[sublettm]

Just installed a new stereo, amp, and speakers in my '85 300D. Everything works fine except I am getting engine noise coming out of the rear speakers as soon as I turn the car on. The noise appears to be related to the auxillary fan. The aux fan comes on as soon as I turn the car to the pre-glow position. I have tried finding a different ground, I also have the power wire hooked directly to the battery. I have installed many stereos in my time, but have never encountered this problem. Any assistance would be greatly appreciated.

Mike