The exposition of Mass Effect: Andromeda is that the Nexus and the five Arks are on a journey to the Andromeda Galaxy in FTL-travel. This travel needs approximately 600 years and the colonists are in cryo-sleep during this time.
But thinking about a journey that lasts 600 years through space, there must be someone responsible for the maintenance of the ships.
All life-supporting systems, the navigation system and also the integrity of the ship as a whole would have to be observed by a crew. I think, a 600-years journey would lead to some marks on every running machine over the time.
I would not guess, that Jien Garson would spend such an enormous amount of money and time into this project and not think about problems like keeping the cryo-chambers and the ships itself running (especially because the true purpose was about saving the humanity from the Reaper Invasion).
The in-game codex mentions that the Hyperion ark has around 20,000 colonists on board.
20,000 humans are in cryogenic stasis aboard Hyperion - Mass Effect Wiki
What I could think about now is that they had a sort of shift-system. Like a small part of the maintenance crew is awake for a few years, caring about the ships and its systems. After the shift they are changing with another group of the crew/colonists. SAM could also play a role in this, as he might observe the ship's systems and maybe wake up the required people once they are needed.
As nothing about this is mentioned in-game, I would like to know if there is any information about this in the background lore of Mass Effect: Andromeda (comics and books or the in-game Codex), which indicates how they managed to challenge this problem?