Just got a brand new GPG13 package unit installed. Idiot who installed it did not put a ptrap into the condensate drain, just open pipe. Now I'm starting to use A/C and I notice no condensate dripping, even after a day of A/C and after I put a ptrap in, and filled it with water to make a seal. Air blows out of the drain (before the ptrap) with the A/C running.
Strange thing is the parts diagram shows the drain connecting a few inches ABOVE the evap drain pan...HUH??