I just installed Alpine CDA9830 on my 97 civic.
I don't know if it is the common problem, but sometimes it makes the motor noise from the deck, I don't know if it's from the headunit or the CD player.
When the system is cold, it's fine, but then when it warms up(say I played it for about 30 minutes), it has that motor noise. When I turn it off or take the face out the noise is gone. It has nothing to do with ignition because the noise is still there when I turn off the ignition and the headunit still on.
The noise is still there even if I take the CD out, so I'm assuming it's from the faceplate, but I don't think there is any motor in the faceplate though.
Does anybody know what it might be?

 

It is a term called "road noise". You can even have the issue when the car is off too. What happens is that the power or ground wire is touching or pinched to metal of the chasis. Check you power and ground. Make sure none is pinched or pressed against the metal of your car. It is a royal bitch to find the problem. I strongly suggest that you try to identify the problem because it migh do some damage down the road (in most cases). If you cant, go to a radio shack and pick up a "ground loop isolator", it will and should solve that problem.

 

Remington knows his ****! he beat me to it.

 

Beat me too it as well =[ This happend to me once and I ignored it and it blew out my head unit while I was driving on the highway at 65 MPH, smoke everywhere .... was not fun...lesson learned