It moves a fair amount of air but.. The range hood on an RV is an exhaust fan. now this fan sends air outside via a "Flapper Valve" On most RV's the Flapper is OUTSIDE and is locked closed by a pair of twist tab. you have to UNLOCK it for it to open and let the air out.
on some (Mine) the flapper is INSIDE. and the latch is up under the hood on the Right. as I recall Pulled out (it's a piece of spring steel) is OPEN but don't quote me on that. I had to take the hood apart to figure it out believe it or not.