We've been burned twice. Once on the Island, for a B2B2B and on the Diamond for a B2B2B. They could not adjust the temperature any more. The problem on the Diamond was no air flow and they gave up fixing it. (Got $1500 in future cruise credits for their inability to fix.) The problem on the Island couldn't be fixed either, but was tolerable - barely.
Keep a record of the temperature in the cabin (78 in the Diamond in the late afternoon until around midnight). Repeatedly request passenger services to fix. That creates a written record. Use that to file a formal complaint at the end of the cruise to corporate.
Other tips, pick a side of the ship that is not exposed to the sun in the afternoon. Example - LA to HI R/T - pick a port cabin. Even if you are interior, the heat load on the other cabins will decrease your A/C capacity. Pick a cabin away from the stairwells that go to exterior decks above. The constant opening and closing of access doors allows hotter external air into the stairwells and elevator shafts.