If insulation is coming out of your air conditioing vents most likely you have damage to your duct work. Alot of times in situations where insulation is coming out the air conditioning vents the damage is caused by rodents. There are most likely holes in your duct work allowing the insulation to get inside the duct work or rodents are taking it inside your duct work. If holes are present in your duct system you are allowing air to escape from your duct system or outside air to be drawn in causing your system to be inefficient. You need to have your duct work inspected to locate the damage and have it repaired.