In response to review, sbgarre says ...

I have found that sometimes the vent itself is closed, thereby not allowing the cooling of the room. Not saying that it was a cause in your case, but something to check on just in case. Another cause could have been‚ one‚ of your neighbors‚ leaving their balcony door open, or the thermostat not correctly set.

Regardless, someone should have at least reported to your room to try and fix it.

We learned of the master switch that we were not to touch or it shuts off the A/C! Good thing we learned it early and only played with the switches minimally... We learned on 2 cruises ago... Pack a small travel fan!