Thank you all for your suggestions. I believe the A/C shop put a dye in it. I just found the receipt and they actually wrote "1/2 lb freon and evaporator core leaking". Don't know why the guy told me 2 lbs on the phone. Anyway, I'll try to get it recharged with some stop leak before taking the car apart. Any advice on the type of "Stop Leak" to get, that will not deteriorate in the long run ? Thank you