I was curious if the a/c vent line is supposed to have standing water in the line. It seems to me that this line should be free of anything to include water. The problem I have is that my a/c is leaking under the drip pan and I think it is the vent line clogged up. The drain pan is not full and the drain line going outside is clear.

You should not have standing water in the line or the pan. They are supposed to be pitched. Try fishing around where the pan and pipe are joined. Use a small wire or pipe cleaner and then flush with water.