Yes , quite possible it is out or low on refrigerant. Put your hand on the compressor to feel if it is running - if it is , then it has lost refrigerant. If it has lost refrigerant it has a leak and it has leaked it out in two years. The leak needs to be located and repaired. Just adding refrigerant will only get you by for two years or less.
Thanks for the info. Can a regular ac repairman who works on my exterior unit do this repair?
If he services central AC's he would certainly be qualified to do so . Many of these techs just don't like or won't work on room AC's however.. If you still have the owners manual check the warranty for sealed system problems - it MIGHT be a 5 year warranty, or call where you purchased it to find out. Hopefully you won't need to speak KOREAN to get any information.
Thanks for your help