The cruise maintenance guys have a small device that plugs into the A/C wall control. That device feeds data to a hand held device that tells the tech exactly what they need to know. The tech can tweak the air damper setting which controls the cooling and heating in the cabin. A good tech should be able to switch your cabin A/C damper from burning hot to freezing cold or vice versa.
We've gone that routine a few times & occasionally it'll help but if there's insufficient temperature of air flowing through the ducts it won't do a bit of good.
I even resorted to removing the deflector altogether & inserted some card board into the main duct to deflect more air into the room & still it was hot. There were many others in our section that also had the same problem.
Luckily they changed our cabin for the second leg.
No more old ships for us.....at least the newer designs have individual AC units for each cabin to supplement the AC from the duct work.