2003 C320 Radio Volume

[drbrad]

Vehicle: 2003 C320 4Matic Wagon with Mercedes/Bose Command System.

Problem:
1. When the seat warmers are on high I adjust the volume.
2. When the warmers turn down or off, the volume turns down automatically.

Any idea why? I would assume if it was a voltage problem, the volume would go up when the warmers turned off since more voltage could now go to the amp.

Can someone explain to me why this happens and if there is anything I should look at? The battery is fine and the alternator is good.

Thanks.