Haha!
Well, i found out what it is. Its the rear aircon evaporator's expansion valve. Dunno why but that was it. I ran the engine for 20 minutes inside my garage waited for it and it came. I traced it to the evaporator at the rear. My mechanic confirmed it as well.
Hehehe. Fyi to all that may also experience hearing a cow inside their vans.
cheers!