Couple of possibilities...
1. You don't have the electric option, so there would be no switch.
2. When the electric option is installed there is an off/on switch inside the water heater (from outside the rig). Small switch on the lower left hand side marked On/Off.
3. Look into any cabinet or access panel behind the water heater. Our current rig doesn't have any other switch, but has a regular plug/wall outlet in the cabinet behind the heater. Our last rig had a switch mounted underneath the kitchen cabinets right above the sink area that turned on the AC heater.
