I am new to the Monaco Esquire motorhome. My two speaker mysteries are now solved. The ceiling mounted speakers in the front and back of the cabin are controlled by the dash radio fade setting.
The other mystery is attributed to the standard AM/FM/CD player that is provided with the "built in radio and CD player" option. It is located by the dinette or the curb side living area. Every time the house battery is disconnected the unit's speaker Balance setting is reset to zero. With this setting one of the mid cabin speakers is muted when a stereo signal is played. You must manually change the balance setting to eight to give the left and right stereo channels equal weight. The Balance setting runs from zero to 16.