I'm getting orange peel spraying on oil in high temperatures with an HVLP conversion gun. What's the fix?
Probably both temperature and thinning are an issue, since you are at the extremes for both (very high temperature, and no thinning at all), but there are a LOT of ways to get orange peel, so eliminating it can be a trial and error process.  

It sounds to me like the solvent is evaporating before the paint can flow together on the cabinets.  This is usually a result of some combination of:


low air pressure or fan adjusted too wide
holding gun too far from the surface of the work
temperature is too hot
too little thinner


If your gun is adjusted properly and your technique is good, then I'd thin and try to work earlier in the day before it gets too hot.  Mineral spirits would be preferable over naptha, because naptha evaporates more quickly.