RV furnaces are pretty basic, most have 2 blower motors one for the outside air, combustion and one for circulating the inside air around the heat exchanger. If your blowing a breaker (reset switch) I'd start my taking a look at the motors. It sounds like you may have one that is starting to bind, which would cause an over current situation and activating the reset switch.
It could be as simple as a squirrel cage that's come loose or a bearing that's going dry. Don't know exactly what bearings are being used, most motors like that use a babit (sp) bushing that may need some oil.
Would be interested in knowing the final resolution.