Here's my feedback on using an undersized AC in a large room.
Using 1 ton AC in a 240 sqft room. Generally sellers will advice you to use 2 ton or 3 ton in these cases. 1 ton per 100 sqft. I have used 40% of their recommended capacity.
Still successfully brought down room temperature down to 24 degrees Centigrade when AC was set to "24". And humidity down to 45%, That's "cool" level. Comfortable level is 26C.
Outdoor temperature is 30C and humidity 80%.
So that's pretty much acceptable for our need.
Note for those that were worried if undersized ACs will cool your room enough or not.