Typically there will be some sort of model number somewhere on the rooftop unit under the shroud, or a sticker on the controller in between the condenser and air distribution box, or even just on the inside of the air distribution box. You might even luck out and find the wiring diagram on the controller or condenser unit since they typically have it readily available to help make installation easier. We don't carry Dometic's DuoTherm line so I would have to contact them with the model... view full answer...