Done before, not working for me, and my wife also complain stuffy.

maybe your room has too much airflow? or the aircon didnt suck enough moisture. did you check the humidity level? if you can get the moisture down to between 50-65% you should be comfy though 65% is bordering it. of course you need a rather sealed room as outside has high humidity levels when its not super hot. best controlled with a ventilation system. our house is completely A/Ced this way, fresh air coming only from aireguard fresh air system & bathroom and kitchen suction and the occasional door opening. proper door and window seals prevent humidity creeping inside. if like that you can effectively chill the house to 28° and hover between 45%-65% humidity at all times. That feels pretty comfy and as added bonus you dont have any issues with fungus or mold (too dry). but then mileage might vary. i think you might also need to control airflow to make this really work.

interesting

My room moisture level always remain around 45-55%, usually 45% when i switch on AC at 23c. Very likely is the human factor not the environment. I am a person can handle hot and cold, but not stuffy (stuffy make me vomit) and my daughter will complain "cannot breath". During rainy day when humidity is +80%, room windows are open and switch on Ventilation, we don't feel stuffy and room temperate around 27+-.

interesting. i dont know your personal situation so i cant really comment. 45% is normal for regualr mode and 23° as you set rather low. Personally I cannto stand the rainy day moisture levels so I adjust accordingly. Too bad dry mode doesnt work well for you then - the energy savings would be substantial as every degree you lower your room will roughly increase power needed by 10%.

How to check for humidity?

Hygrometers

lzd a alot

May I know where did you buy that hygrometer or where I can find a good one?

http://my.rs-online.com/web/ sells a cheap one: http://my.rs-online.com/web/p/digital-thermometers/4086109/

more (and better) choices:

http://www.unidex.my/products/thermo-hygrometers.html

Or build your own

https://www.lelong.com.my/arduino-dht11-tem...8-01-Sale-P.htm

I wonder how accurate is the reading.

Actually not that bad for the price. I made a temperature reading (another shield, not this) pretty accurate, i was testing it using Raspberry i2s bus logging server room data and push the data into cloud. I would say tolerance of +-5%

Cause this kits make it as hobby/DIY/project. Doesn't require accuracy as long as it cheap for hobby.

So I have this impression that this kits are not accurate.

There are cheap build sensor and also expensive sensor. Nevertheless is very often use for prototyping, once have a proper design and spec out, will have to properly build and test on different environment.

Do you've a dehumidifier or dehumidifier + air purifier 2 in 1?

why? i have an aircon which is a dehumidifier already. and i dont have to empty a bucket with it either

a dehumidifier is essentially a portable aircon. only difference is that the heat is not blown outside but "kept" in the room.

May I know what brand and price is this Air Con?

any inverter will do. i use pana

i brought at daiso rm 5.90 only...

may I ask how many airconds you have in house, and how many hours you normally use, and your electricity bill per month (average)?