Here is a link to the unit that I have in the coach (and just ordered).
It appears it might have both hydraulic and electric components to it, but not sure how to separate them out. The entire unit was $250 delivered, so I figured I would get that in my hands first and then proceed.
Right now, my fan is constantly on HIGH. Great for temps in hot weather, but in regular temps I think the coach runs colder than it should in the first hour or so. Not to mention gas mileage is probably down 1mpg and it's just kind of irritating when going over dusty campground roads.