I figured that the drain was plugged with crud. I have had many vehicle do the exact same thing happen. I think it's better to use a shop vac to get the crud out instead of pushing it in with compressed air. Since it will cause it to plug again when it start to come back out. I rigged up a hose to my shop vac so it will fit fairly snug and suck out as much as I can and not to have to worry about it for awhile.

 

I thought about rigging a hose to the shop vac also. I a little worried about compressed air after hearing all the horror stories of the bad leak that comes in from the fresh air duct in the cowl. I thought compressed air might blow out the gasket in the evaporator box.