If you have the MotorAid option the heater coil may be part of the system. The MotorAid usually has a heater core with a fan that blows hot into the motor home. There should be switch on the dash to turn the fan on. Mine was behind a door below the refrigerator and that compartment always got very warm when we were driving down the road.
The system uses engine coolant for the heater and also heats the water in the water heater while driving. There is a heat exchanger tube welded to the back of the water heater tank.
Clay WA5NMR - Ex Snowbird - 1 year, Ex Full timer for 11 years - 2004 Winnebago Sightseer 35N Workhorse chassis. Honda Accord toad.