Install the outdoor unit at shaded area or atleast create some shade for it, like those green shaded clothes. If its tripping at high temperatures like you said, then that's due to compressor overheating since you put outdoor unit in direct sunlight.
Similar thing used to happen to my friend who had installed the outdoor unit at roof in direct sunlight which made outdoor unit burning hot. He re-installed in on wall in shaded area and now it works perfectly fine.
A good idea is to always install outdoor unit at shaded area which is not directly exposed to sunlight majority of the times.