Ultima xtc suddenly stops

Hi.
I have an ultima xtc reefer unit on my trailer. I have this problem for some time now.
The unit runs perfectly and does its job them all of a sudden it just stops. Doesnt matter if its set to start stop or continoues mode. And the unit doesnt reach the setpoin yet. On the main screen everything disappear. It turns black. Then couple seconds later the unit starts to turn back on like when im turning the on/off switch on. Anybody has any idea what it could be?
Thanks in advance

So when it does run,does it achieve set temperature?if so it sounds like a wiring connection fault not too sure if that unit has an inline fuse from the battery which goes to on/off switch,,time to look in the box where the micro is and look for connection issues.