I arrived and checked in then called Block for the roof access code. During this I spoke with the Block engineer for this building and he relayed to me what he had discovered when he was on the roof with snow a few days ago. I confirmed his findings such as economizer was closed and all removable panels are in place. I opened the return and supply panels and removed the pre-filters to inspect the return and supply duct areas where the unit meets the curb. There was no signs of water or past water at these junctions. The evaporator drain for the air-conditioner was cleared however the p-trap was frozen with water in it. This is normal as water is supposed to fill the trap. At this time due to no more snow and no signs of water entering the duct work I do not have a 100% diagnosis however causes were eliminated today. Possibilities that remain are the roof leaking, possibly someone turned on the A/C on accident and the drain was blocked with Ice, or a cause that will need to