How can I keep the water/condensation from accumulating on my a/c vents. They are constantly dripping water.?

Under your air handler (closet or attic) there is a drain pan. This pan should have a pipe going to a drain, or just outside. If this is clogged, it could cause your symptoms. This is in need of immediate repair, if you leave it your duct work can rust through, or you will grow mold, or damage the drywall/plaster. It should be an easy fix.

There is WAY too much moisture in the air and therefore, the house. The reason moisture drips from the vents is that they are cold and moisture from the air condenses on cold surfaces and drips. You need to find the source of that moisture and eliminate it. Is water collecting on the floor or elsewhere around the furnace unit where the cooling unit is located? (Is the condensate drain from the pan under the evaporator coil blocked?) Are you trying to cool the outside? That is, is moist air being introduced into the house by openings (windows, doors, or other)?

What I have found to be most common is.....

The grilles will "sweat" when there is very poor insulation in the attic. Go up in the attic and see if there is insulation covering your outlets (or very THIN insulatin covering them). If not, you're gonna get condensation. If this is the case, go to the hardware store, buy some batt insulation, and cover the tops of the registers in the attic..... Put several batts over top of each register. so that none of the attic air can get to them.

Simply put.... 100 degrees above the register, 60 something degrees coming out of the register = condensation. Check this before you do anything else.....

your ac should drip if you have a window unit. The ac unit removes excess moisture from the air in your house and cools the air as it recycles it back into the house

The first thing you always do is make sure your AC unit is thoroughly clean. If your filter is dirty, you will not get enough air flow to remove the humidity. Your ducts will be below the dew point of the air in your house and they will sweat.

CLEAN CLEAN CLEAN