What could be the problem if water is found on the inside of the house when the central air is used and could it be a blocked pipe?

All central A.C. systems have a drain. Look for the fan some where in the house, mine is in my guest bath. When you open the door covering the whole thing (you should not have to take anything apart) just open door and you should see a drip pan and a pipe leading from it which is a drain pipe. I have had to blow mine out with air which is how you do it and then i pour a cup a bleach down it every 6 months and that keeps it from stopping up ever again