Thought this might be helpful to someone. If you have the Jensen AWM975 unit in your entertainment center, and you press the A, B, or C zones and two of the three will not work, here is something I discovered.
My bedroom and outside speakers would not work so I figured it was faulty wiring. The solution was simple, the Fader and the Balance must be set to "0" within the audio controls or it will block the other zones from playing.
Push the "Volume" knob, and with each push it will scroll through Bass, Treble, Fader and Balance. Set your Balance and Fader to "0" and check to see if your zones begin to work. Worked for me!
Hope this helps someone!