Water stains on the ceiling can be caused from a few different things from your air conditioner. The most common is a condensate drain that is stopping up causing water to drain on the ceiling. A few others deal with air conditioning components not properly insulated in the attic. Ducts not properly insulated will cause condensation to form on them and drip on your ceiling. The condensate drain and suction refrigerant line both will also drip on the ceiling from condensation forming on them if not insulated properly. The best thing to do is figure out the source of the water. If the water is from a secondary/emergency drain pan or from the air handler itself, most likely it is a stopped up drain. See the stopped up drain faq, If it is coming from a duct the duct most likely needs to be reinsulted or replaced. If it is coming off copper or drain line it needs to insulated with pipe insulation,
Tags: condensation