Onan Generator Overheats and shuts down.

This can be a problem based on a few factors - Placement of the genset, ambient temperature, how hard it's working, and how fast you are travelling. I used to have this issue on ours. It would happen when the factors above caused it to overheat. My genset sits behind the front driver's side wheel. Coincidentally right behind the engine manifold. So it gets a lot of heat just from the engine, add to that the heat of the road, and if you are stuck in traffic you aren't moving air over it, on a hot day (85+) and finally, most entry MH's are poorly insulated so that the AC works non stop to combat the ambient temperature thus putting a constant heavy load on the genset, and it's bound to overheat. Simple solution for mine was to add 2 vents in the bin door - almost like floor vents, one with fins facing forward to route air into the genset bin, and one with fins facing toward the rear to allow hot air to escape. Thor paid to have my dealer do the fix. Aesthetically it looks factory. That was over a year ago and haven't had the issue since.