After a week + battling with the Sonata AC, here are my findings.
I changed the Compressor (recon)
Changed the Condensor (new)
Flushed the AC system
Changed the Valve

Aircond now works perfectly.. sometimes with flaws:
Reduced "coldness" when stuck in major traffic jam
Sometimes could hear either "refrigerant" or "pulley" sound when AC is on (dunno where the exact sound comes from but no leaking of refrigerant)
ONCE. the AC completely shut down and blows hot air. I shut down my car, turn it back on and the AC returns to normal (like how you boot the computer and things go back to normal)

I dont know what else to do. I am lost lol ~ Bring it to workshop to check, cant check anything coz AC is perfectly fine. Hiccups a lot. But overall, I am still loving my YF haha