A/C evaporator not dripping

[Heavysledz]

My A/C evaporator drain is not dripping any water and the air smells musty and stale when you first turn the A/C on. I think I found what appears to be the drain location. Mine doesn't have a tube connected to it so I was skeptical that I had the right location. I stuck a screw driver in the hole about 6-8" before it bottomed out and it appeared to be clean inside and nothing came out or was blocking the hole. I blew compressed air in the hole as well and nothing came out and didn't appear to beobstructed. I started the truck and ran the A/C and I could feel cool air blowing out the hole so I assume this is the drain. I let it idle with the air on for 10 minutes and not a drip.....I drove it for a few miles and checked it when I got home...no drips.....any ideas where to go from here?